CERTIFICATIONS PURSUANT TO SECTION 906 OF THE
                          SARBANES-OXLEY ACT OF 2002

David P. Butler and Gerard K. O'Reilly, Co-Principal Executive Officers, and
Gregory K. Hinkle, Principal Financial Officer, of Dimensional Investment Group
Inc., a Maryland corporation (the "Registrant"), each certify that:

    1. The Registrant's periodic report on Form N-CSR/A for the period ended
       April 30, 2018 (the "Report") fully complies with the requirements of
       Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934,
       as amended, as applicable; and

    2. The information contained in the Report fairly presents, in all material
       respects, the financial condition and results of operations of the
       Registrant.

By:  /s/ David P. Butler
     ------------------------------------
     David P. Butler
     Co-Principal Executive Officer
     Dimensional Investment Group Inc.

Date:  August 31, 2018

By:  /s/ Gerard K. O'Reilly
     ------------------------------------
     Gerard K. O'Reilly
     Co-Principal Executive Officer
     Dimensional Investment Group Inc.

Date:  August 31, 2018

By:  /s/ Gregory K. Hinkle
     ------------------------------------
     Gregory K. Hinkle
     Principal Financial Officer
     Dimensional Investment Group Inc.

Date:  August 31, 2018