<PAGE>
                                                             Exhibit 10.20(b)
                              SECOND AMENDMENT TO
                      O'SULLIVAN INDUSTRIES HOLDINGS, INC.
                           DEFERRED COMPENSATION PLAN

       WHEREAS, O'Sullivan Industries Holdings, Inc. (the "Company") has
established a nonqualified deferred compensation plan for the benefit of a
select group of management and highly compensation employees; and

       WHEREAS, pursuant to the terms of the Plan, the Company reserved the
right to amend the Plan from time to time in its discretion; and

       WHEREAS, the Plan was heretofore amended by the First Amendment dated
effective as of July 1, 1997; and

       WHEREAS, the Company desires to further amend the Plan as set forth
below;

       NOW, THEREFORE, in consideration of these premises, the Plan is amended
as follows, effective as of June 30, 1999, and subject to the closing of the
Agreement and Plan of Merger Between OSI Acquisition, Inc. and O'Sullivan
Industries Holdings, Inc. dated as of May 17, 1999:

       A. Article IV is amended to read in its entirety as follows:

                       ARTICLE IV--INVESTMENT OF ACCOUNTS

        4.1 INVESTMENT ALTERNATIVES. Each Participant may elect to have his
    Elective Deferral Contributions Account, Matching Contributions Account and
    his Profit Sharing Contributions Account allocated among the following two
    investment alternatives. The investment percentage for each investment
    alternative selected by the Participant must be a multiple of 25%.

        (a) Fixed Interest Rate. The amount owed by the Company with respect to
    any amount allocated to the Fixed Interest Rate investment shall be
    determined by crediting earnings on such amount (whether gains or losses)
    equal to the percentage changes in the PIMCO Total Return II Fund, assuming
    reinvestment of all dividends and distributions. Earnings shall be credited
    to Accounts as of the last day of each calendar quarter.

        (b) S&P 500. The amount owed by the Company with respect to any amount
    allocated to the S&P 500 investment shall be determined by crediting
    earnings on such amount (whether gains or losses) equal to the percentage
    changes in the Vanguard 500 Index Fund, assuming reinvestment of all
    dividends and distributions. Earnings shall be credited to Accounts as of
    the last day of each calendar quarter.

        The Participant shall make his initial investment selection by filing a
    form with the Administrator at least 15 days prior to the effective date of
    his participation.

        4.2 TRANSFERS BETWEEN INVESTMENTS. The Participant's investment
    direction shall remain in effect unless and until the Participant replaces
    the direction in accordance with this Section 4.2. Participants may change
    the percentages of their future Elective Deferral Contributions, Matching
    Contribution, and Profit Sharing Contributions, or the percentages of their
    existing Account balances, among the investment alternatives as of
    January 1 and July 1 of each Plan Year (each, an "Allocation Date") by
    filing a form with the Administrator. Any election must be filed on or
    before 15 days prior to the effective date.

        4.3 ELIMINATION OF THE PHANTOM STOCK MEASURING INVESTMENT. Effective as
    of July 1, 1999, O'Sullivan Industries Holdings, Inc. common stock (the
    "Phantom Stock Unit" investment) shall cease to be a measuring investment
    with respect to Elective Deferral Contributions, Matching Contributions
    and/or Profit Sharing Contributions credited to a Participant's Accounts, in
    accordance with the other provisions of this Plan, on or after such date.
    Further, any amounts credited to a Participant's Accounts which are deemed
    invested in Phantom Stock Units immediately prior to the closing of the
    Agreement and Plan of Merger

                                       1
<PAGE>
    Between OSI Acquisition, Inc. and O'Sullivan Industries Holdings, Inc. dated
    as of May 17, 1999, shall be valued as of the most recent trading date
    immediately preceding such Closing and an equivalent amount shall be deemed
    invested in the S&P 500 investment unless and until changed at a later date
    in the manner set forth in Section 4.2.

       B. Section 5.5 is amended to read in its entirety as follows:

        5.5 DISTRIBUTION OF ELECTIVE DEFERRALS. Prior to the beginning of each
    Plan Year, at the time that the Participant elects to make Elective Deferral
    Contributions for such Plan Year, the Participant may elect to receive a
    distribution of any such Elective Deferral Contributions that are not
    eligible for a Matching Contribution under Section 3.2, at any time after
    the end of the fifth Plan Year following the Plan Year during which such
    election is made. All distributions shall be made in lump sum cash payment.
    Any election made pursuant to this Section 5.5 shall be made on a form
    prescribed by the Administrator and shall be irrevocable once made.

       C. Section 5.6 is amended to read in its entirety as follows:

        5.6 METHOD OF PAYMENT. A Participant may elect distribution of his or
    her Accounts in a lump sum or in installments over a period of years (not to
    exceed ten). Any such election must be made no later than twelve months
    prior to the time a Participant first becomes eligible to receive a
    distribution of his Accounts under the Plan. If the Participant elects
    installment payments, the unpaid amount shall continue to be invested as
    provided in Article IV and shall continue to accrue earnings until paid. All
    distributions shall be made in cash. Any election pursuant to this
    Section 5.6 shall be made on a form prescribed by the Administrator and
    shall be irrevocable once made.

       D. Section 5.7 is amended by deleting the last sentence thereunder
reading: "Notwithstanding the foregoing, the restrictions specified in
Section 4.2 shall apply to the election by an Officer, as defined in
Section 4.2, to receive a distribution under this Section."

       E. Notwithstanding the foregoing, this Amendment is expressly conditioned
upon the closing of the Agreement and Plan of Merger Between OSI
Acquisition, Inc. and O'Sullivan Industries Holdings, Inc. dated as of May 17,
1999, and if such closing does not occur, then this Amendment shall be null and
void.

                                       2

<PAGE>
                                 SIGNATURE PAGE

       IN WITNESS WHEREOF, this Second Amendment has been duly executed as of
the     day of              , 1999.

<TABLE>
<S>                                                    <C>
                                                       O'SULLIVAN INDUSTRIES HOLDINGS, INC.

                                                       By:                /s/ RICHARD D. DAVIDSON
                                                            --------------------------------------------------
                                                                            Richard D. Davidson
                                                                   PRESIDENT AND CHIEF EXECUTIVE OFFICER
</TABLE>

ATTEST:

<TABLE>
<S>                                                    <C>

 /s/ ROWLAND H. GEDDIE, III
-------------------------------------------
Rowland H. Geddie, III
Vice President, General Counsel and Secretary

</TABLE>

                                       3