EXHIBIT 31.1

                                  CERTIFICATION

I, Thomas A. Ritter, President and Chief Executive Officer, certify, that:

         1. I have reviewed this annual report on Form 10-K/A of ACNB
Corporation, Inc.;

         2. Based on my knowledge, the 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;

         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;

         4. The registrant's other certifying officers and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial
reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the
registrant and we have:

                  (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 annual report is being prepared;

                  (b) designed such internal control over financial reporting,
         or caused such internal control over financial reporting to be designed
         under our supervision, to provide reasonable assurance regarding the
         reliability of financial reporting and the preparation of financial
         statements for external purposes in accordance with generally accepted
         accounting principles;

                  (c) evaluated the effectiveness of the registrant's disclosure
         controls and procedures and presented in this annual report our
         conclusions about the effectiveness of the disclosure controls and
         procedures, as of the end of the period covered by this annual report
         based upon such evaluation; and

                  (d) 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

         5. The registrant's other certifying officer and I have disclosed,
based on our most recent evaluation, of internal control over financial



reporting, to the registrant's auditors and the audit committee of the
registrant's board of directors (or persons performing the equivalent
functions):

                  (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

                  (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.

Date:    April 29, 2005              By:   /S/ THOMAS A. RITTER
                                           -------------------------------------
                                           Thomas A. Ritter
                                           President and Chief Executive Officer