SCHEDULE 14A INFORMATION

                  Proxy Statement Pursuant to Section 14(a) of
              the Securities Exchange Act of 1934 (Amendment No. )

                           Filed by the Registrant / /
                 Filed by a Party other than the Registrant /X/
                           Check the appropriate box:
                         / / Preliminary Proxy Statement
     / / CONFIDENTIAL, FOR USE OF THE COMMISSION ONLY (AS PERMITTED BY RULE
                                  14A-6(E)(2))
                         / / Definitive Proxy Statement
                       /X/ Definitive Additional Materials
                 / / Soliciting Material Pursuant to Rule 14a-12

                           ART TECHNOLOGY GROUP, INC.


                (Name of Registrant as Specified In Its Charter)

Mitchell Wright Technology Group, LLC, SSH Partners I, LP, Mitchell-Wright, LLC,
Arcadia Partners, L.P., Arcadia Capital Management, LLC, James Dennedy and
Richard Rofe

    (Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):
/X/ No fee required

/ / Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11
(1) Title of each class of securities to which transaction applies:

(2) Aggregate number of securities to which transaction applies:

(3) Per unit price or other underlying value of transaction computed pursuant to
Exchange Act Rule 0-11 (set forth the amount on which the filing fee is
calculated and state how it was determined):

(4) Proposed maximum aggregate value of transaction:

(5) Total fee paid:

/ / Fee paid previously with preliminary materials.
/ / Check box if any part of the fee is offset as provided by Exchange Act Rule
0-11(a)(2) and identify the filing for which the offsetting fee was paid
previously. Identify the previous filing by registration statement number, or
the Form or Schedule and the date of its filing.
(1) Amount Previously Paid:

(2) Form, Schedule or Registration Statement No.:

(3) Filing Party:

(4) Date Filed:



Attached as Exhibit 1 is a letter to shareholders delivered by Mitchell-Wright
Technology Group, LLC to shareholders of the issuer together with its definitive
proxy statement on October 13, 2004.



Exhibit 1



                      Mitchell-Wright Technology Group, LLC
                         8060 Montgomery Road, Suite 205
                              Cincinnati, OH 45236


October 12, 2004


Dear Fellow Shareholder:

     We believe that the proposed acquisition of Primus Knowledge Solutions,
Inc. ("Primus") by Art Technology Group, Inc. ("ATG"), under management's
current plan, may result in further deterioration of shareholder value.
Management's plan fails to extract the necessary cost synergies, and fails to
protect the balance sheet. In our opinion, Art Technology Group, Inc. can be
profitable today on a stand-alone basis, and can thrive without the proposed
Primus acquisition.

     We strongly believe in ATG's greatest assets - its customer base, strong
product innovations and high customer loyalty - and we believe these assets
should be protected and profitably enhanced. We have always had enormous respect
for ATG, for the outstanding achievements of its employees and for the culture
of innovation and integrity that has contributed to its success.

     As a stockholder of ATG, we believe that the ATG board owes a duty to
pursue stockholder value and to guide ATG to profitable growth for the benefit
of its stockholders. Our decision to solicit your proxy is entirely motivated by
what we believe is in the best interests of stockholders from a financial
perspective.

   -------------------------------------------------------------------------

      Vote AGAINST the merger agreement. Tell the Board that you want it to
   guide the Company to profitable operations, enhance the balance sheet and
                 retain control of our strategic alternatives.

   -------------------------------------------------------------------------

     We believe stockholders should vote AGAINST the issuance of shares of ATG
common stock in connection with the proposed merger. Consider the following:

o    ATG'S FINANCIAL POSITION WILL DETERIORATE
     In our opinion, neither ATG nor Primus has demonstrated a management
     culture or commitment to profitability. The proposed merger combines two
     companies with a history of losses. The combination creates an entity with
     merely the possibility of greater revenue but with the CERTAINTY of
     increased operating expenses. Should the additional revenue expected by
     management from the merger fail to materialize or the full level of cost
     reductions not be implemented, ATG's cash balance would quickly erode to a
     level well below the $30 million cash level cited by management as a
     critical threshold.

o    ATG'S STRATEGIC POSITION WILL NOT MATERIALLY IMPROVE
     While the proposed merger would enhance ATG's product portfolio, ATG would
     still be a software company with less than $100 million of revenue on an
     enterprise basis. ATG would still lack the size and breadth of offering
     required to be truly competitive in the software industry. In addition, the
     weak financial position that we believe would result from the merger would
     limit ATG's strategic options in the future.

o    THE INTEGRATION RISK OF THE PROPOSED MERGER IS SUBSTANTIAL
     We believe that the odds are against the success of this merger given
     management's post-merger operating plan. The complexity of putting two
     companies together, in a difficult economy, when each company is unable to
     consistently produce profits, presents daunting and unacceptable
     challenges.

o    THE FINANCIAL IMPACT ON ATG STOCKHOLDERS WILL BE NEGATIVE
     Management has asked shareholders to accept tremendous risk by approving
     the merger agreement without, in our opinion, providing an action plan that
     would produce financial results to justify the additional financial risk,
     operating risk and dilution that would result from the merger.



     We urge you to vote AGAINST the proposed merger. Send a clear message to
the Board and management of ATG that you believe this merger is not necessary
and will harm the long-term value of your investment.


Very truly yours,



James H. Dennedy
Managing Partner
Mitchell-Wright Technology Group, LLC


     ----------------------------------------------------------------------

       IF YOU HAVE ANY QUESTIONS OR REQUIRE ASSISTANCE IN VOTING YOUR BLUE
     PROXY CARD, PLEASE CALL INNISFREE M&A INCORPORATED, THE FIRM ASSISTING
              US IN OUR SOLICITATION, TOLL-FREE AT 1-888-750-5834.

     ----------------------------------------------------------------------