EXHIBIT 31a
                  CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER
            PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

         I, Larry J. Miller, President and CEO, certify, that:

         1.       I have reviewed this quarterly report on Form 10-Q of Codorus
Valley Bancorp, Inc;

         2.       Based on my knowledge, this quarterly 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 quarterly report;

         3.       Based on my knowledge, the financial statements, and other
financial information included in this quarterly 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 quarterly
report;

         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-15(e) and 15d-15(e) 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 report
                           is being prepared;

                  (b)      [Reserved][Paragraph omitted pursuant to SEC Release
                           Nos. 33-8238 and 34-47986]

                  (c)      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

                  (d)      Disclosed in this report any change in the
                           registrant's internal control over financial
                           reporting that occurred during the registrant's first
                           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
registrant's board of directors (or persons performing the equivalent function):

                  (a)      All significant deficiencies and material weaknesses
                           in the design or operation of the 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 company's internal control over financial
                           reporting.

Date:    May 11, 2004                     /s/ Larry J. Miller
                                          --------------------------
                                          Larry J. Miller, President and CEO

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