Exhibit No. EX-99.h.4.d.


                                 FEE WAIVER AND
                          EXPENSE ASSUMPTION AGREEMENT

     FEE WAIVER AND  EXPENSE  ASSUMPTION  AGREEMENT  dated as of August 7, 2006,
between DFA  Investment  Dimensions  Group  Inc.,  a Maryland  corporation  (the
"Fund"),  on behalf of Emerging Markets Social Core Portfolio (the "Portfolio"),
and Dimensional Fund Advisors Inc., a Delaware corporation ("Dimensional").

     WHEREAS, Dimensional has entered into an Investment Advisory Agreement with
the Fund, on behalf of the  Portfolio,  pursuant to which  Dimensional  provides
investment  management services for the Portfolio,  and for which Dimensional is
compensated based on the average net assets of such Portfolio; and

     WHEREAS,  the Fund and  Dimensional  have determined that it is appropriate
and in the best  interests of the  Portfolio and its  shareholders  to limit the
expenses of the Portfolio;

     NOW, THEREFORE, the parties hereto agree as follows:

     1.   Fee Waiver and Expense  Assumption by Dimensional.  Dimensional agrees
          to waive  all or a portion  of its  management  fee and to assume  the
          expenses  of the  Portfolio  to the  extent  necessary  to  limit  the
          Portfolio's  expenses on an  annualized  basis to 0.85% of its average
          net assets.

     2.   Duty to  Reimburse  Dimensional.  If,  at any  time,  the  Portfolio's
          expenses  are  less  than  0.85%  of  its  average  net  assets  on an
          annualized  basis,  the  Fund,  on  behalf  of  the  Portfolio,  shall
          reimburse  Dimensional for any fees previously  waived and/or expenses
          previously assumed to the extent that the amount of such reimbursement
          does not cause the Portfolio's  annualized expenses to exceed 0.85% of
          its average net assets.  There shall be no  obligation of the Fund, on
          behalf of the Portfolio,  to reimburse  Dimensional for fees waived or
          expenses assumed by Dimensional  more than thirty-six  months prior to
          the date of any such reimbursement.

     3.   Assignment.   No  assignment  of  this  Agreement  shall  be  made  by
          Dimensional without the prior consent of the Fund.

     4.   Duration and  Termination.  This  Agreement  shall  continue in effect
          until August 7, 2007,  and shall  continue in effect from year to year
          thereafter,  unless  and until the Fund or  Dimensional  notifies  the
          other party to the Agreement, at least thirty days prior to the end of
          the one-year  period for the Portfolio,  of its intention to terminate
          the Agreement.  This Agreement shall automatically  terminate upon the
          termination of the Investment Advisory Agreement for the Portfolio.

     IN WITNESS  WHEREOF,  the parties hereto have executed this Agreement as of
the date first written above.

DFA INVESTMENT DIMENSIONS GROUP INC.               DIMENSIONAL FUND ADVISORS INC.

By:  /s/ Jeff J. Jeon                              By:  /s/ Michael T. Scardina
Name:  Jeff J. Jeon                                Name:  Michael T. Scardina
Title:   Vice President                            Title:  VP & CFO