EXHIBIT 31.1

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

      I, George H. Glatfelter II, certify that:

1.    I have reviewed this Annual Report on Form 10-K for the year ended
      December 31, 2005 of P.H. Glatfelter Company ("Glatfelter");

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 period 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.    Glatfelter'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 Glatfelter 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
            Glatfelter, 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 Glatfelter'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 Glatfelter's internal control
            over financial reporting that occurred during Glatfelter's most
            recent fiscal quarter (the fourth fiscal quarter in the case of an
            annual report) that has materially affected, or is reasonably likely
            to materially affect, Glatfelter's internal control over financial
            reporting; and

5.    Glatfelter's other certifying officer and I have disclosed, based on our
      most recent evaluation of internal control over financial reporting, to
      Glatfelter's auditors and the audit committee of the Glatfelter'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 Glatfelter'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 Glatfelter's internal
            control over financial reporting.

                       Date: March 13, 2006   By:   /s/ George H. Glatfelter II
                                                   -----------------------------
                                                         George H. Glatfelter II
                                                         Chairman and Chief
                                                           Executive Officer