UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM 8-K/A

                                (Amendment No. 1)

                                 CURRENT REPORT

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

Date of report (Date of earliest event reported): March 3, 2005

                                 S1 Corporation
               (Exact Name of Registrant as Specified in Charter)

          Delaware                  000-24931                58-2395199
(State or Other Jurisdiction (Commission File Number)      (IRS Employer
     of Incorporation)                                  Identification No.)

               3500 Lenox Road, Suite 200, Atlanta, Georgia 30326
               (Address of Principal Executive Offices) (Zip Code)

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


          (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:

|_|  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))


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



Item 2.02   Results of Operations and Financial Condition
- ---------------------------------------------------------

     On March 3, 2005, S1 Corporation  ("S1") issued a press release  correcting
and replacing the press release issued  announcing the results of operations for
the quarter and year ended  December  31,  2004.  In the first table  "Financial
Guidance for Q1, Q4 and Full Year 2005" Consolidated Revenue for the Full Year -
High is 295 (stated 290).  Also,  the fourth table  "Statements of Operations by
Segment" should read: For the Quarter Ended September 30, 2004 (stated  December
31, 2004).

     The corrected  press release is filed as Exhibit 99.1 to this report.  Also
on March 3, 2005, S1 held a conference call during which S1 discussed its fourth
quarter and year end 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)  642-1687,
Access # 3925458.  The replay  will be active  until 5:00 p.m.  EDT on March 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

Exhibits No.    Description
- ------------    -----------

99.1            Corrected Press Release dated March 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.

Date: March 4, 2005          S1 Corporation
                              (Registrant)

                             By:  /s/ Richard P. Dobb
                                  ----------------------------
                                  Vice President, General Counsel & Secretary



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



                                  Exhibit Index


Exhibit No.                Description
- -----------                -----------

     99.1                  Corrected Press release dated March 3, 2005.