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                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

       Date of Report (Date of earliest event reported): November 3, 2005

                                 S1 CORPORATION
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             (Exact name of registrant as specified in its charter)

          DELAWARE                       000-24931               58-2395199
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(State or other jurisdiction            (Commission             (IRS Employer
     of incorporation)                  File Number)         Identification No.)

               3500 Lenox Road, Suite 200, Atlanta, Georgia 30326
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                    (Address of principal executive offices)

       Registrant's telephone number, including area code: (404) 923-3500

                                 Not Applicable
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          (Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions (see General Instruction A.2. below):

[ ]  Written communications pursuant to Rule 425 under the Securities
     Act (17 CFR 230.425)

[ ]  Soliciting material pursuant to Rule 14a-12 under the Exchange
     Act (17 CFR 240.14a-12)

[ ]  Pre-commencement communications pursuant to Rule 14d-2(b) under the
     Exchange Act (17 CFR 240.14d-2(b))

[ ]  Pre-commencement communications pursuant to Rule 13e-4(c) under the
     Exchange Act (17 CFR 240.13e-4(c)) Rule 425, Rule 14a-12 and
     Instruction 2 to Rule 14d-2(b)(2)

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ITEM 2.02   RESULTS OF OPERATIONS AND FINANCIAL CONDITION

        On November 3, 2005, S1 Corporation ("S1") issued a press release
announcing the results of operations for the third quarter ended September 30,
2005. That press release is furnished as Exhibit 99.1 to this report. Also on
November 3, 2005, S1 held a conference call during which S1 discussed its third
quarter results and presented certain other material relating to S1 and its
operations. A replay of the conference call is available for playback two hours
after the conference call is complete by dialing (800) 626-7250, Access
#1655761. The replay will be active until 5:00 p.m. EST on November 10, 2005.

        In accordance with General Instruction B.2 of Form 8-K, the information
in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed
"filed" for the purposes of Section 18 of the Securities Exchange Act of 1934,
as amended, or otherwise subject to the liability of that section, nor shall it
be deemed incorporated by reference in any filing under the Securities Act of
1933, as amended, except as shall be expressly set forth by specific reference
in such a filing.

ITEM 9.01 FINANCIAL STATEMENTS AND EXHIBITS

(c)  Exhibits

Exhibit No.    Description
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99.1           Press release dated November 3, 2005.



                                   SIGNATURES

        Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                             S1 CORPORATION
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                                             (Registrant)


                                             /s/ Richard P. Dobb
                                             -----------------------------------
                                             Richard P. Dobb
                                             Vice President, General Counsel and
                                             Secretary

Date: November 3, 2005



                                  EXHIBIT INDEX

Exhibit No.    Description
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 99.1           Press release dated November 3, 2005.