<PAGE>

                                                                    Exhibit 31.1

CERTIFICATION :

I, Daniel P. McCartney, Chief Executive Officer, certify that:

     1.   I have reviewed this quarterly report on Form 10-Q of Healthcare
          Services Group, Inc.;

     2.   Based on my knowledge, this 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 periods covered by this report;

     3.   Based on my knowledge, the financial statements, and other financial
          information included in this 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
          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)) and internal
          control over financial reporting ( as defined in Exchange Act Rules
          13a-15(f) and 15d-15(f)) for the registrant and 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)   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 quarterly 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 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
          registrant's Board of Directors.

          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: July 21, 2006


                                        /s/ Daniel P. McCartney
                                        ----------------------------------------
                                        Daniel P. McCartney
                                        Chief Executive Officer