content: <HTML>
  <HEAD>
  <TITLE>sv8</TITLE>
  </HEAD>
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  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>As filed with the Securities and Exchange Commission on June&nbsp;30, 2006</B>
  </DIV>
  
  
  <DIV align="right" style="font-size: 10pt; margin-top: 0pt"><B>Registration No.&nbsp;333-</B>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
  </DIV>
  
  
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 1pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  <DIV align="center" style="font-size: 14pt; margin-top: 12pt"><B>UNITED STATES<BR>
  SECURITIES AND EXCHANGE COMMISSION</B>
  </DIV>
  
  <DIV align="center" style="font-size: 12pt"><B>Washington, D.C. 20549</B>
  </DIV>
  
  <DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 25%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  
  <DIV align="center" style="font-size: 18pt; margin-top: 12pt"><B>FORM S-8</B>
  </DIV>
  
  
  <DIV align="center" style="font-size: 12pt; margin-top: 12pt"><B>REGISTRATION STATEMENT<BR>
  UNDER<BR>
  THE SECURITIES ACT OF 1933</B>
  </DIV>
  
  <DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 25%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  
  <DIV align="center" style="font-size: 24pt; margin-top: 12pt"><B>Art Technology Group, Inc.</B>
  </DIV>
  
  <DIV align="center" style="font-size: 10pt">(Exact name of registrant as specified in its charter)</DIV>
  
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="48%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="48%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="center" valign="top"><B>Delaware</B><BR>
  (State or other jurisdiction of incorporation or organization)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top"><B>04-3141918</B><BR>
  (I.R.S. employer identification no.)</TD>
  </TR>
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="center" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="center" valign="top"><B>25 First Street, Second Floor, Cambridge, Massachusetts</B><BR>
  (Address of principal executive offices)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="center" valign="top"><B>02141</B><BR>
  (Zip code)</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>1999 Employee Stock Purchase Plan</B><BR>
  (Full title of the plan)
  </DIV>
  
  <DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 25%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>Robert D. Burke<BR>
  President and Chief Executive Officer<BR>
  Art Technology Group, Inc.<BR>
  25 First Street, Second Floor<BR>
  Cambridge, Massachusetts 02141</B><BR>
  (Name and address of agent for service)
  </DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>(617)&nbsp;386-1000</B><BR>
  (Telephone number, including area code, of agent for service)
  </DIV>
  
  <DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 25%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>WITH COPIES TO:<BR>
  John D. Patterson, Jr.<BR>
  Robert W. Sweet, Jr.<BR>
  Foley Hoag </B><FONT style="font-variant: SMALL-CAPS"><B>LLP</B></FONT><BR>
  <B>155 Seaport Boulevard<BR>
  Boston, Massachusetts 02210<BR>
  (617)&nbsp;832-1000</B>
  </DIV>
  
  <DIV align="center"><DIV style="font-size: 3pt; margin-top: 16pt; width: 25%; border-top: 1px solid #000000">&nbsp;</DIV></DIV>
  
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>CALCULATION OF REGISTRATION FEE</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="1%">&nbsp;</TD>
      <TD width="28%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD><!-- VRule -->
      <TD width="2%">&nbsp;</TD>
      <TD width="13%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD><!-- VRule -->
      <TD width="2%">&nbsp;</TD>
      <TD width="13%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD><!-- VRule -->
      <TD width="2%">&nbsp;</TD>
      <TD width="13%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD><!-- VRule -->
      <TD width="2%">&nbsp;</TD>
      <TD width="13%">&nbsp;</TD>
  
      <TD width="1%">&nbsp;</TD>
  </TR><TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="15" style="border-bottom: 3px double #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="center"><B>Title of</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Amount</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Proposed maximum</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Proposed maximum</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Amount of</B></TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="center"><B>securities to be</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>to be</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>offering price</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>aggregate</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>registration</B></TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">    <TD width="1%">&nbsp;</TD>
  
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><B>registered</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><B>registered</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><B>per share</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><B>offering price</B></TD>
      <TD style="border-right: 1px solid #000000">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 0px solid #000000"><B>fee</B></TD>
      <TD width="1%">&nbsp;</TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD width="1%" style="border-top: 1px solid #000000">&nbsp;</TD>
                      <TD align="left" valign="top" style="border-top: 1px solid #000000">Common stock, $0.01 par value (1)
  </TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
      <TD align="center" valign="top" style="border-top: 1px solid #000000">1,500,000
  </TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
  
  <TD align="center" valign="top" style="border-top: 1px solid #000000">$2.77
  (2)
  </TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
  
  <TD align="center" valign="top" style="border-top: 1px solid #000000">$4,155,000
  </TD>
      <TD style="border-right: 1px solid #000000; border-top: 1px solid #000000">&nbsp;</TD>
      <TD style="border-top: 1px solid #000000">&nbsp;</TD>
  
  <TD align="center" valign="top" style="border-top: 1px solid #000000">$445</TD>
      <TD width="1%" style="border-top: 1px solid #000000">&nbsp;</TD>
  </TR>
  <TR style="font-size: 1px" valign="bottom">
      <TD nowrap align="left" colspan="15" style="border-top: 3px double #000000">&nbsp;</TD>
  </TR>
  
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(1)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Each share includes one right to purchase shares of ATG&#146;s series A junior participating
  preferred stock pursuant to the terms of ATG&#146;s rights agreement dated September&nbsp;26, 2001.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="margin-top: 6pt">
  <TABLE width="100%" border="0" cellpadding="0" cellspacing="0" style="font-size: 10pt">
  
  <TR valign="top" style="font-size: 10pt; color: #000000; background: transparent">
      <TD width="1%" nowrap align="left">(2)</TD>
      <TD width="1%">&nbsp;</TD>
      <TD>Calculated pursuant to Rules 457(c) and (h)(1) under the Securities Act of 1933 based on
  the average of the high and low sale prices of the common stock as reported on the Nasdaq
  National Market on June&nbsp;27, 2006.</TD>
  </TR>
  
  </TABLE>
  </DIV>
  
  <DIV style="width: 100%; border-bottom: 1pt solid black; margin-top: 10pt; font-size: 1pt">&nbsp;</DIV>
  <DIV style="width: 100%; border-bottom: 2pt solid black; font-size: 1pt">&nbsp;</DIV>
  
  
  
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  
  
  
  
  
  <!-- TOC -->
  <A name="toc"><DIV align="CENTER" style="page-break-before:always"><U><B>TABLE OF CONTENTS</B></U></DIV></A>
  
  <P><CENTER>
  <TABLE border="0" width="90%" cellpadding="0" cellspacing="0">
  <TR>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="3%"></TD>
  	<TD width="76%"></TD>
  </TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#000">Item&nbsp;5.&nbsp;&nbsp;&nbsp; Interests of Named Experts and Counsel.</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#001">Item&nbsp;8.&nbsp;&nbsp;&nbsp; Exhibits.</A></TD></TR>
  <TR><TD></TD><TD colspan="8"><A HREF="#002">Item&nbsp;9.&nbsp;&nbsp;&nbsp; Undertakings.</A></TD></TR>
  <TR><TD colspan="9"><A HREF="#003">SIGNATURES</A></TD></TR>
  <TR><TD colspan="9"><A HREF="#004">POWER OF ATTORNEY</A></TD></TR>
  <TR><TD colspan="9"><A HREF="#005">EXHIBIT INDEX</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b61419atexv5w1.htm">Ex-5.1 Legal opinion of Foley Hoag LLP</A></TD></TR>
  <TR><TD colspan="9"><A HREF="b61419atexv23w1.htm">Ex-23.1 Consent of Ernst & Young LLP</A></TD></TR>
  </TABLE>
  </CENTER>
  <!-- /TOC -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;This registration statement covers 1,500,000 shares of common stock issuable pursuant to
  our 1999 Employee Stock Purchase Plan. These shares are in addition to the 5,000,000 shares of
  common stock registered pursuant to the registration statements on Form S-8, File Nos. 333-83321,
  333-100003 and 333-106058, which we filed with the Securities and Exchange Commission on July&nbsp;20,
  1999, September&nbsp;23, 2002 and June&nbsp;12, 2003, respectively.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The contents of our registration statements on Form S-8, File Nos. 333-83321, 333-100003 and
  333-106058, are incorporated herein by reference.
  </DIV>
  <!-- link2 "Item&nbsp;5.&nbsp;&nbsp;&nbsp; Interests of Named Experts and Counsel." -->
  <DIV align="left"><A NAME="000"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;5.&nbsp;&nbsp;&nbsp; Interests of Named Experts and Counsel.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The validity of the securities we are registering is being passed upon by Foley Hoag LLP,
  Boston, Massachusetts.
  </DIV>
  <!-- link2 "Item&nbsp;8.&nbsp;&nbsp;&nbsp; Exhibits." -->
  <DIV align="left"><A NAME="001"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;8.&nbsp;&nbsp;&nbsp; Exhibits.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The following exhibits are included as part of this registration statement.
  </DIV>
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="8%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="36%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="10%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="8%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="20%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="7" style="border-bottom: 1px solid #000000"><B>Incorporated by reference</B></TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Filed with</B></TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD nowrap align="CENTER"><B>Exhibit</B></TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>this Form</B></TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Filing date with</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3"><B>Exhibit</B></TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD nowrap align="CENTER" style="border-bottom: 1px solid #000000"><B>Number</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>Description</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>S-8</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>Form</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>SEC</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3" style="border-bottom: 1px solid #000000"><B>number</B></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated Certificate
  of Incorporation of Art
  Technology Group, Inc.
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">S-8
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">June&nbsp;12, 2003
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="BOTTOM">4.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated By-Laws of
  Art Technology Group, Inc.
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">S-3
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">July&nbsp;6, 2001
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="BOTTOM">4.2</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.3
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Specimen common stock certificate
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">S-1/A
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">July&nbsp;13, 1999
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="BOTTOM">4</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.4
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Rights Agreement dated September
  26, 2001 between Art Technology
  Group, Inc. and EquiServe Trust
  Company, N.A., as rights agent
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">8-K
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="BOTTOM">October&nbsp;2, 2001
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="BOTTOM">4.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">5.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Legal opinion of Foley Hoag LLP
  </TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="BOTTOM">X</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Ernst &#038; Young LLP
  </TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="BOTTOM">X</TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Foley Hoag LLP
  (contained in Exhibit&nbsp;5.1)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="BOTTOM">X</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">24.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Power of Attorney (included on
  the signature page of this
  registration statement)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="BOTTOM">X</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  <!-- link2 "Item&nbsp;9.&nbsp;&nbsp;&nbsp; Undertakings." -->
  <DIV align="left"><A NAME="002"></A></DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 12pt"><B>Item&nbsp;9.&nbsp;&nbsp;&nbsp; Undertakings.</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;The undersigned registrant hereby undertakes to:
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(a)&nbsp;(1)&nbsp;To file, during any period in which offers or sales are being made, a post-effective
  amendment to this registration statement:
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i)&nbsp;To include any prospectus required by section 10(a)(3) of the Securities Act of
  1933;
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii)&nbsp;To reflect in the prospectus any facts or events arising after the effective
  date of the registration statement (or the most recent post-effective amendment thereof)
  which, individually or in the aggregate, represent a fundamental change in the
  </DIV>
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">information set forth in the registration statement. Notwithstanding the foregoing,
  any increase or decrease in volume of securities offered (if the total dollar value of
  securities offered would not exceed that which was registered) and any deviation from the
  low or high end of the estimated maximum offering range may be reflected in the form of
  prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
  changes in volume and price represent no more than 20% change in the maximum aggregate
  offering price set forth in the &#147;Calculation of Registration Fee&#148; table in the effective
  registration statement; and
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii)&nbsp;To include any material information with respect to the plan of distribution
  not previously disclosed in the registration statement or any material change to such
  information in the registration statement;
  </DIV>
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">provided, however, that Paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the information
  required to be included in a post-effective amendment by those paragraphs is contained in reports
  filed with or furnished to the Commission by the registrant pursuant to section 13 or section 15(d)
  of the Securities Exchange Act of 1934 that are incorporated by reference in the registration
  statement.
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2)&nbsp;That, for the purpose of determining any liability under the Securities Act of 1933, each
  such post-effective amendment shall be deemed to be a new registration statement relating to the
  securities offered therein, and the offering of such securities at that time shall be deemed to be
  the initial bona fide offering thereof.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(3)&nbsp;To remove from registration by means of a post-effective amendment any of the securities
  being registered which remain unsold at the termination of the offering.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(4)&nbsp;That, for the purpose of determining liability of the registrant under the Securities Act
  of 1933 to any purchaser in the initial distribution of the securities, the undersigned registrant
  undertakes that in a primary offering of securities of the undersigned registrant pursuant to this
  registration statement, regardless of the underwriting method used to sell the securities to the
  purchaser, if the securities are offered or sold to such purchaser by means of any of the following
  communications, the undersigned registrant will be a seller to the purchaser and will be considered
  to offer or sell such securities to such purchaser:
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i)&nbsp;Any preliminary prospectus or prospectus of the undersigned registrant relating
  to the offering required to be filed pursuant to Rule&nbsp;424;
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii)&nbsp;Any free writing prospectus relating to the offering prepared by or on behalf of
  the undersigned registrant or used or referred to by the undersigned registrant;
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii)&nbsp;The portion of any other free writing prospectus relating to the offering
  containing material information about the undersigned registrant or its securities provided
  by or on behalf of the undersigned registrant; and
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iv)&nbsp;Any other communication that is an offer in the offering made by the undersigned
  registrant to the purchaser.
  </DIV>
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(b)&nbsp;The undersigned registrant hereby undertakes that, for purposes of determining any
  liability under the Securities Act of 1933, each filing of the registrant&#146;s annual report pursuant
  to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 that is incorporated by
  reference in the registration statement shall be deemed to be a new registration statement relating
  to the securities offered therein, and the offering of such securities at that time shall be deemed
  to be the initial bona fide offering thereof.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(c)&nbsp;Insofar as indemnification for liabilities arising under the Securities Act of 1933 may
  be permitted to directors, officers and controlling persons of the registrant pursuant to the
  foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the
  Securities and Exchange Commission such indemnification is against public policy as expressed in
  the Act and is, therefore, unenforceable. In the event that a claim for indemnification against
  such liabilities (other than the payment by the registrant of expenses incurred or paid by a
  director, officer or controlling person of the registrant in the successful defense of any action,
  suit or proceeding) is asserted by such director, officer or controlling person in connection with
  the securities being registered, the registrant will, unless in the opinion of its counsel the
  matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the
  question whether such indemnification by it is against public policy as expressed in the Act and
  will be governed by the final adjudication of such issue.
  </DIV>
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  <!-- link1 "SIGNATURES" -->
  <DIV align="left"><A NAME="003"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>SIGNATURES</B>
  </DIV>
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it
  has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and
  has duly caused this registration statement to be signed on its behalf by the undersigned,
  thereunto duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on this 30th
  day of June, 2006.
  </DIV>
  
  <TABLE width="100%" border="0" cellspacing="0" cellpadding="0" style="font-size: 10pt">
  <TR>
      <TD width="48%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="35%">&nbsp;</TD>
      <TD width="15%">&nbsp;</TD>
  </TR>
  <TR>
      <TD valign="top" align="left">&nbsp;</TD>
      <TD colspan="3" align="left"><FONT style="font-variant: SMALL-CAPS"><B>Art Technology Group, Inc.</B></FONT><BR>
  &nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD valign="top">By:&nbsp;&nbsp;</TD>
      <TD colspan="2" style="border-bottom: 1px solid #000000" align="left">/s/ Robert D. Burke
  &nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD colspan="2" align="left">Robert D. Burke&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR><TR>
      <TD align="left">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD colspan="2" align="left">President and Chief Executive Officer&nbsp;</TD>
      <TD>&nbsp;</TD>
  </TR>
  <TR>
      <TD colspan="5">&nbsp;</TD>
  </TR>
  </TABLE>
  <!-- link1 "POWER OF ATTORNEY" -->
  <DIV align="left"><A NAME="004"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>POWER OF ATTORNEY</B>
  </DIV>
  
  
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;KNOW ALL BY THESE PRESENTS that each individual whose signature appears below hereby
  constitutes and appoints Robert D. Burke and Julie M.B. Bradley, and each of them, his or her true
  and lawful attorneys-in-fact and agents with full power of substitution, for him or her and in his
  or her name, place and stead, in any and all capacities, to sign any and all amendments (including
  post-effective amendments) to this registration statement, and to file the same, with all exhibits
  thereto, and all documents in connection therewith, with the Securities and Exchange Commission,
  granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do
  and perform each and every act and thing which they, or any of them, may deem necessary or
  advisable to be done in connection with this registration statement, as fully to all intents and
  purposes as he or she might or could do in person, hereby ratifying and confirming all that said
  attorneys-in-fact and agents or any of them, or any substitute or substitutes for him or her, or
  any or all of them, may lawfully do or cause to be done by virtue hereof.
  </DIV>
  
  <DIV align="left" style="font-size: 10pt; margin-top: 6pt">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Pursuant to the requirements of the Securities Act, this registration statement has been
  signed by the following persons in the indicated capacities as of June&nbsp;30, 2006.
  </DIV>
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="47%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="47%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
  
  <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>Signature</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>Title</B></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="center" nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ Robert D. Burke
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Robert D. Burke</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT">
  President, Chief Executive Officer and Director<BR>
  <I>(Principal Executive Officer)</I></TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ Julie M.B. Bradley
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Julie M.B. Bradley</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT">
  Senior Vice President, Chief Financial Officer<BR>
  <I>(Principal Financial and Accounting Officer)</I></TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ Daniel C. Regis
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Daniel C. Regis</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT" valign="top">
  Chairman of the Board</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="47%">&nbsp;</TD>
      <TD width="5%">&nbsp;</TD>
      <TD width="47%">&nbsp;</TD>
  </TR>
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom"><!-- Blank Space -->
      <TD align="right">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="center" nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ Michael A. Brochu
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Michael A. Brochu</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT" valign="top">
  Director</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ David B. Elsbree
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  David B. Elsbree</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT" valign="top">
  Director</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ John R. Held
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  John R. Held</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT" valign="top">
  Director</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ Ilene H. Lang
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Ilene H. Lang</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT" valign="top">
  Director</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ Mary Makela
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Mary Makela</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT" valign="top">
  Director</TD>
  </TR>
  <TR valign="bottom" style="padding-top: 1em">
      <TD align="left" valign="top">/s/ Phyllis S. Swersky
  <DIV style="font-size: 1pt; border-bottom: 1px solid #000000">&nbsp;</DIV>
  Phyllis S. Swersky</TD>
      <TD>&nbsp;</TD>
      <TD align="LEFT" valign="top">
  Director</TD>
  </TR>
  <!-- End Table Body -->
  </TABLE>
  </DIV>
  
  
  <P align="center" style="font-size: 10pt">&nbsp;
  </DIV>
  
  <!-- PAGEBREAK -->
  <P><HR noshade><P>
  <H5 align="left" style="page-break-before:always"><A HREF="#toc">Table of Contents</A></H5><P>
  
  <DIV style="font-family: 'Times New Roman',Times,serif">
  
  <!-- link1 "EXHIBIT INDEX" -->
  <DIV align="left"><A NAME="005"></A></DIV>
  
  <DIV align="center" style="font-size: 10pt; margin-top: 18pt"><B>EXHIBIT INDEX</B>
  </DIV>
  
  <DIV align="center">
  <TABLE style="font-size: 10pt" cellspacing="0" border="0" cellpadding="0" width="100%">
  <!-- Begin Table Head -->
  <TR valign="bottom">
      <TD width="8%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="36%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="10%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="8%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="20%">&nbsp;</TD>
      <TD width="2%">&nbsp;</TD>
      <TD width="3%">&nbsp;</TD>
      <TD width="1%">&nbsp;</TD>
      <TD width="4%">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="7" style="border-bottom: 1px solid #000000"><B>Incorporated by reference</B></TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Filed with</B></TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3">&nbsp;</TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD nowrap align="CENTER"><B>Exhibit</B></TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>this Form</B></TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center"><B>Filing date with</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3"><B>Exhibit</B></TD>
  </TR>
  <TR style="font-size: 10pt" valign="bottom">
      <TD nowrap align="CENTER" style="border-bottom: 1px solid #000000"><B>Number</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>Description</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>S-8</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>Form</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" style="border-bottom: 1px solid #000000"><B>SEC</B></TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="center" colspan="3" style="border-bottom: 1px solid #000000"><B>number</B></TD>
  </TR>
  
  <!-- End Table Head -->
  <!-- Begin Table Body -->
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated Certificate
  of Incorporation of Art
  Technology Group, Inc.
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">S-8
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">June&nbsp;12, 2003
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="bottom">4.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Amended and Restated By-Laws of
  Art Technology Group, Inc.
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">S-3
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">July&nbsp;6, 2001
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="bottom">4.2</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.3
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Specimen common stock certificate
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">S-1/A
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">July&nbsp;13, 1999
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="bottom">4</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">4.4
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Rights Agreement dated September
  26, 2001 between Art Technology
  Group, Inc. and EquiServe Trust
  Company, N.A., as rights agent
  </TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">8-K
  </TD>
      <TD>&nbsp;</TD>
      <TD align="right" valign="bottom">October&nbsp;2, 2001
  </TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="bottom">4.1</TD>
      <TD nowrap valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">5.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Legal opinion of Foley Hoag LLP
  </TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="bottom">X</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.1
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Ernst &#038; Young LLP
  </TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="bottom">X</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
      <TD>&nbsp;</TD>
      <TD nowrap align="right" valign="top">&nbsp;</TD>
      <TD align="right" valign="top">&nbsp;</TD>
      <TD valign="top">&nbsp;</TD>
  </TR>
  <TR valign="bottom">
      <TD align="right" valign="top"><DIV style="margin-left:0px; text-indent:-0px">23.2
  </DIV></TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">Consent of Foley Hoag LLP
  (contained in Exhibit&nbsp;5.1)
  </TD>
      <TD>&nbsp;</TD>
      <TD align="CENTER" valign="bottom">X</TD>
      <TD>&nbsp;</TD>
      <TD align="left" valign="top">&nbsp;</TD>
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text: sv8
  Table of Contents
  As filed with the Securities and Exchange Commission on June 30, 2006
  Registration No. 333-
  UNITED STATES
  SECURITIES AND EXCHANGE COMMISSION
  Washington, D.C. 20549
  FORM S-8
  REGISTRATION STATEMENT
  UNDER
  THE SECURITIES ACT OF 1933
  Art Technology Group, Inc.
  (Exact name of registrant as specified in its charter)
  Delaware
  (State or other jurisdiction of incorporation or organization)
  04-3141918
  (I.R.S. employer identification no.)
  25 First Street, Second Floor, Cambridge, Massachusetts
  (Address of principal executive offices)
  02141
  (Zip code)
  1999 Employee Stock Purchase Plan
  (Full title of the plan)
  Robert D. Burke
  President and Chief Executive Officer
  Art Technology Group, Inc.
  25 First Street, Second Floor
  Cambridge, Massachusetts 02141
  (Name and address of agent for service)
  (617) 386-1000
  (Telephone number, including area code, of agent for service)
  WITH COPIES TO:
  John D. Patterson, Jr.
  Robert W. Sweet, Jr.
  Foley Hoag
  LLP
  155 Seaport Boulevard
  Boston, Massachusetts 02210
  (617) 832-1000
  CALCULATION OF REGISTRATION FEE
  Title of
  Amount
  Proposed maximum
  Proposed maximum
  Amount of
  securities to be
  to be
  offering price
  aggregate
  registration
  registered
  registered
  per share
  offering price
  fee
  Common stock, $0.01 par value (1)
  1,500,000
  $2.77
  (2)
  $4,155,000
  $445
  (1)
  Each share includes one right to purchase shares of ATG's series A junior participating
  preferred stock pursuant to the terms of ATG's rights agreement dated September 26, 2001.
  (2)
  Calculated pursuant to Rules 457(c) and (h)(1) under the Securities Act of 1933 based on
  the average of the high and low sale prices of the common stock as reported on the Nasdaq
  National Market on June 27, 2006.
  TABLE OF CONTENTS
  Item 5.    Interests of Named Experts and Counsel.
  Item 8.    Exhibits.
  Item 9.    Undertakings.
  SIGNATURES
  POWER OF ATTORNEY
  EXHIBIT INDEX
  Ex-5.1 Legal opinion of Foley Hoag LLP
  Ex-23.1 Consent of Ernst & Young LLP
  Table of Contents
  This registration statement covers 1,500,000 shares of common stock issuable pursuant to
  our 1999 Employee Stock Purchase Plan. These shares are in addition to the 5,000,000 shares of
  common stock registered pursuant to the registration statements on Form S-8, File Nos. 333-83321,
  333-100003 and 333-106058, which we filed with the Securities and Exchange Commission on July 20,
  1999, September 23, 2002 and June 12, 2003, respectively.
  The contents of our registration statements on Form S-8, File Nos. 333-83321, 333-100003 and
  333-106058, are incorporated herein by reference.
  Item 5.    Interests of Named Experts and Counsel.
  The validity of the securities we are registering is being passed upon by Foley Hoag LLP,
  Boston, Massachusetts.
  Item 8.    Exhibits.
  The following exhibits are included as part of this registration statement.
  Incorporated by reference
  Filed with
  Exhibit
  this Form
  Filing date with
  Exhibit
  Number
  Description
  S-8
  Form
  SEC
  number
  4.1
  Amended and Restated Certificate
  of Incorporation of Art
  Technology Group, Inc.
  S-8
  June 12, 2003
  4.1
  4.2
  Amended and Restated By-Laws of
  Art Technology Group, Inc.
  S-3
  July 6, 2001
  4.2
  4.3
  Specimen common stock certificate
  S-1/A
  July 13, 1999
  4
  4.4
  Rights Agreement dated September
  26, 2001 between Art Technology
  Group, Inc. and EquiServe Trust
  Company, N.A., as rights agent
  8-K
  October 2, 2001
  4.1
  5.1
  Legal opinion of Foley Hoag LLP
  X
  23.1
  Consent of Ernst & Young LLP
  X
  23.2
  Consent of Foley Hoag LLP
  (contained in Exhibit 5.1)
  X
  24.1
  Power of Attorney (included on
  the signature page of this
  registration statement)
  X
  Item 9.    Undertakings.
  The undersigned registrant hereby undertakes to:
  (a) (1) To file, during any period in which offers or sales are being made, a post-effective
  amendment to this registration statement:
  (i) To include any prospectus required by section 10(a)(3) of the Securities Act of
  1933;
  (ii) To reflect in the prospectus any facts or events arising after the effective
  date of the registration statement (or the most recent post-effective amendment thereof)
  which, individually or in the aggregate, represent a fundamental change in the
  Table of Contents
  information set forth in the registration statement. Notwithstanding the foregoing,
  any increase or decrease in volume of securities offered (if the total dollar value of
  securities offered would not exceed that which was registered) and any deviation from the
  low or high end of the estimated maximum offering range may be reflected in the form of
  prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
  changes in volume and price represent no more than 20% change in the maximum aggregate
  offering price set forth in the "Calculation of Registration Fee" table in the effective
  registration statement; and
  (iii) To include any material information with respect to the plan of distribution
  not previously disclosed in the registration statement or any material change to such
  information in the registration statement;
  provided, however, that Paragraphs (a)(1)(i) and (a)(1)(ii) do not apply if the information
  required to be included in a post-effective amendment by those paragraphs is contained in reports
  filed with or furnished to the Commission by the registrant pursuant to section 13 or section 15(d)
  of the Securities Exchange Act of 1934 that are incorporated by reference in the registration
  statement.
  (2) That, for the purpose of determining any liability under the Securities Act of 1933, each
  such post-effective amendment shall be deemed to be a new registration statement relating to the
  securities offered therein, and the offering of such securities at that time shall be deemed to be
  the initial bona fide offering thereof.
  (3) To remove from registration by means of a post-effective amendment any of the securities
  being registered which remain unsold at the termination of the offering.
  (4) That, for the purpose of determining liability of the registrant under the Securities Act
  of 1933 to any purchaser in the initial distribution of the securities, the undersigned registrant
  undertakes that in a primary offering of securities of the undersigned registrant pursuant to this
  registration statement, regardless of the underwriting method used to sell the securities to the
  purchaser, if the securities are offered or sold to such purchaser by means of any of the following
  communications, the undersigned registrant will be a seller to the purchaser and will be considered
  to offer or sell such securities to such purchaser:
  (i) Any preliminary prospectus or prospectus of the undersigned registrant relating
  to the offering required to be filed pursuant to Rule 424;
  (ii) Any free writing prospectus relating to the offering prepared by or on behalf of
  the undersigned registrant or used or referred to by the undersigned registrant;
  (iii) The portion of any other free writing prospectus relating to the offering
  containing material information about the undersigned registrant or its securities provided
  by or on behalf of the undersigned registrant; and
  (iv) Any other communication that is an offer in the offering made by the undersigned
  registrant to the purchaser.
  Table of Contents
  (b) The undersigned registrant hereby undertakes that, for purposes of determining any
  liability under the Securities Act of 1933, each filing of the registrant's annual report pursuant
  to section 13(a) or section 15(d) of the Securities Exchange Act of 1934 that is incorporated by
  reference in the registration statement shall be deemed to be a new registration statement relating
  to the securities offered therein, and the offering of such securities at that time shall be deemed
  to be the initial bona fide offering thereof.
  (c) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may
  be permitted to directors, officers and controlling persons of the registrant pursuant to the
  foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the
  Securities and Exchange Commission such indemnification is against public policy as expressed in
  the Act and is, therefore, unenforceable. In the event that a claim for indemnification against
  such liabilities (other than the payment by the registrant of expenses incurred or paid by a
  director, officer or controlling person of the registrant in the successful defense of any action,
  suit or proceeding) is asserted by such director, officer or controlling person in connection with
  the securities being registered, the registrant will, unless in the opinion of its counsel the
  matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the
  question whether such indemnification by it is against public policy as expressed in the Act and
  will be governed by the final adjudication of such issue.
  Table of Contents
  SIGNATURES
  Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it
  has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and
  has duly caused this registration statement to be signed on its behalf by the undersigned,
  thereunto duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on this 30th
  day of June, 2006.
  Art Technology Group, Inc.
  By:
  /s/ Robert D. Burke
  Robert D. Burke
  President and Chief Executive Officer
  POWER OF ATTORNEY
  KNOW ALL BY THESE PRESENTS that each individual whose signature appears below hereby
  constitutes and appoints Robert D. Burke and Julie M.B. Bradley, and each of them, his or her true
  and lawful attorneys-in-fact and agents with full power of substitution, for him or her and in his
  or her name, place and stead, in any and all capacities, to sign any and all amendments (including
  post-effective amendments) to this registration statement, and to file the same, with all exhibits
  thereto, and all documents in connection therewith, with the Securities and Exchange Commission,
  granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do
  and perform each and every act and thing which they, or any of them, may deem necessary or
  advisable to be done in connection with this registration statement, as fully to all intents and
  purposes as he or she might or could do in person, hereby ratifying and confirming all that said
  attorneys-in-fact and agents or any of them, or any substitute or substitutes for him or her, or
  any or all of them, may lawfully do or cause to be done by virtue hereof.
  Pursuant to the requirements of the Securities Act, this registration statement has been
  signed by the following persons in the indicated capacities as of June 30, 2006.
  Signature
  Title
  /s/ Robert D. Burke
  Robert D. Burke
  President, Chief Executive Officer and Director
  (Principal Executive Officer)
  /s/ Julie M.B. Bradley
  Julie M.B. Bradley
  Senior Vice President, Chief Financial Officer
  (Principal Financial and Accounting Officer)
  /s/ Daniel C. Regis
  Daniel C. Regis
  Chairman of the Board
  Table of Contents
  /s/ Michael A. Brochu
  Michael A. Brochu
  Director
  /s/ David B. Elsbree
  David B. Elsbree
  Director
  /s/ John R. Held
  John R. Held
  Director
  /s/ Ilene H. Lang
  Ilene H. Lang
  Director
  /s/ Mary Makela
  Mary Makela
  Director
  /s/ Phyllis S. Swersky
  Phyllis S. Swersky
  Director
  Table of Contents
  EXHIBIT INDEX
  Incorporated by reference
  Filed with
  Exhibit
  this Form
  Filing date with
  Exhibit
  Number
  Description
  S-8
  Form
  SEC
  number
  4.1
  Amended and Restated Certificate
  of Incorporation of Art
  Technology Group, Inc.
  S-8
  June 12, 2003
  4.1
  4.2
  Amended and Restated By-Laws of
  Art Technology Group, Inc.
  S-3
  July 6, 2001
  4.2
  4.3
  Specimen common stock certificate
  S-1/A
  July 13, 1999
  4
  4.4
  Rights Agreement dated September
  26, 2001 between Art Technology
  Group, Inc. and EquiServe Trust
  Company, N.A., as rights agent
  8-K
  October 2, 2001
  4.1
  5.1
  Legal opinion of Foley Hoag LLP
  X
  23.1
  Consent of Ernst & Young LLP
  X
  23.2
  Consent of Foley Hoag LLP
  (contained in Exhibit 5.1)
  X
  24.1
  Power of Attorney (included on
  the signature page of this
  registration statement)
  X