Exhibit 31.1

CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

| I, Robert S.   Bowen, certify that:                                                                                                                                                                                                                                                                                                   |
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| 1. I have   reviewed this annual report on Form 10-K of Group 1 Software, Inc.;                                                                                                                                                                                                                                                       |
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| 2. Based on   my knowledge, this annual report does not contain any untrue statement of a   material fact or omit to state a material fact necessary to make the   statements made, in light of the circumstances under which such statements   were made, not misleading with respect to the period covered by this annual   report; |
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| 3. Based on   my knowledge, the financial statements, and other financial information   included in this annual report, fairly present in all material respects the   financial condition, results of operations and cash flows of the registrant   as of, and for, the periods presented in this annual report;                      |
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| 4. The   registrant’s other certifying officer and I are responsible for establishing   and maintaining disclosure controls and procedures (as defined in Exchange   Act Rules 13a-14 and 15d-14) for the registrant and we have:                                                                                                |
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|                                                                                                                                                                                                                                                                                                                                  | a) | Designed   such disclosure controls and procedures, or caused such disclosure controls   and procedures to be designed under our supervision, to ensure that material   information relating to the registrant, including its consolidated   subsidiaries, is made known to us by others within those entities,   particularly during the period in which this report is being prepared; |
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|                                                                                                                                                                                                                                                                                                                                  | b) | Evaluated   the effectiveness of the registrant’s disclosure controls and procedures and   presented in this report our conclusions about the effectiveness of the   disclosure controls and procedures, as of the end of the period covered by   this report based on such evaluation; and |
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|                                                                                                                                                                                                                                                                                                                                  | c) | Disclosed in   this report any change in the registrant’s internal control over financial   reporting that occurred during the registrant’s most recent fiscal quarter   that has materially affected, or is reasonably likely to materially affect,   the registrant’s internal control over financial reporting; and |
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| 5. The   registrant’s other certifying officer and I have disclosed, based on our most   recent evaluation, to the registrant’s auditors and the audit committee of   registrant’s board of directors (or persons performing the equivalent   function):                                                               |
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|                                                                                                                                                                                                                                                                                                                                  | a) | All   significant deficiencies and material weaknesses in the design or operation   of internal control over financial reporting which are reasonably likely to   adversely affect the registrant’s ability to record, process, summarize and   report financial information; and |
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|                                                                                                                                                                                                                                                                                                                                  | b) | Any fraud,   whether or not material, that involves management or other employees who have   a significant role in the registrant’s internal control over financial   reporting. |

 

|   | /s/ ROBERT S. BOWEN       |
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|   |                           |
|   | Chief   Executive Officer |
|   | June 14, 2004             |