<Page>

                                                       Exhibit 99.Code of Ethics

EFFECTIVE DATE: OCTOBER 5, 2004                                 CONFIDENTIAL AND
                                                                     PROPRIETARY

                           CODE OF BUSINESS ETHICS FOR
                   PRINCIPAL EXECUTIVE AND FINANCIAL OFFICERS

                      DFA INVESTMENT DIMENSIONS GROUP INC.
                  DIMENSIONAL EMERGING MARKETS VALUE FUND INC.
                        DIMENSIONAL INVESTMENT GROUP INC.
                        THE DFA INVESTMENT TRUST COMPANY

I.    COVERED OFFICERS AND PURPOSES OF THE CODE

      The Boards of Directors/Trustees (together, the "Boards") of DFA
Investment Dimensions Group Inc., Dimensional Emerging Markets Value Fund Inc.,
Dimensional Investment Group Inc. and The DFA Investment Trust Company (each a
"Fund," and together, the "Funds") have adopted this Code of Business Ethics for
Principal Executive and Financial Officers (the "Code"). The Code applies to the
Funds' principal executive officers and principal financial officers (together,
the "Covered Officers"), and is adopted to promote:

      -     honest and ethical conduct, including the ethical handling of
            conflicts of interest;

      -     full, fair, accurate, timely and understandable disclosure in
            reports and documents that a Fund files with, or submits to, the
            U.S. Securities and Exchange Commission (the "SEC"), and in other
            public communications made by the Funds;

      -     compliance with applicable laws and governmental rules and
            regulations;

      -     the prompt internal reporting of violations of the Code to the
            appropriate person(s) identified in the Code; and

      -     accountability for adherence to the Code.

II.   COVERED OFFICERS SHOULD "ADHERE TO A HIGH STANDARD OF BUSINESS ETHICS"

      Each Covered Officer owes a duty to the Funds to adhere to a high standard
of business ethics and should be sensitive to situations that may give rise to
actual, as well as apparent, conflicts of interests.

      Each Covered Officer shall:

      -     observe all laws and governmental rules and regulations, accounting
            standards and Fund policies;

      -     adhere to a high standard of business ethics; and

      -     place the interests of the Funds before the Covered Officer's own
            personal interests.

      All activities of Covered Officers should be guided by and adhere to these
fiduciary standards.

[DIMENSIONAL LOGO]

<Page>

III.  COVERED OFFICERS SHOULD HANDLE ETHICALLY CONFLICTS OF INTEREST

      GUIDING PRINCIPLES. A "conflict of interest" occurs when a Covered
Officer's private interests interfere with the interests of, or his service to,
the Funds. A conflict of interest can arise when a Covered Officer takes actions
or has interests that may make it difficult to perform his Fund work objectively
and effectively. For example, a conflict of interest would arise if a Covered
Officer, or a member of his family, receives improper personal benefits as a
result of his positions with the Funds. In addition, the Funds must be sensitive
to situations that create apparent, if not actual, conflicts of interest.
Service to the Funds should not be subordinated to personal gain and advantage.

      Certain conflicts of interest covered by this Code arise out of the
relationships between Covered Officers and the Funds that already are subject to
conflict of interest provisions in the Investment Company Act of 1940, as
amended (the "1940 Act"), and the Investment Advisers Act of 1940, as amended
(the "Advisers Act"). For example, Covered Officers may not individually engage
in certain transactions (such as the purchase or sale of securities or other
property) with the Funds because of the Covered Officers' status as "affiliated
persons" of the Funds. The compliance programs and procedures of the Funds and
Dimensional Fund Advisors Inc., the Funds' investment advisor and administrator
(the "Advisor"), are designed to prevent, or identify and correct, violations of
these provisions. This Code does not, and is not intended to, repeat or replace
those compliance programs and procedures. Covered Officers must in all cases
comply with applicable statutes and regulations.

      Although typically not presenting an opportunity for improper personal
benefit, conflicts of interest arise from, or as a result of, the contractual
relationships between the Funds and the Advisor, of which the Covered Officers
are also officers or employees. As a result, it is recognized by the Boards
that, subject to the Advisor's fiduciary duties to the Funds, the Covered
Officers will, in the normal course of their duties (whether formally for the
Funds or for the Advisor, or for both), be involved in establishing policies and
implementing decisions that will have different effects on the Advisor and the
Funds. The Boards recognize that the participation of the Covered Officers in
such activities is inherent in the contractual relationships between the Funds
and the Advisor, and is consistent with the expectation of the Boards of the
performance by the Covered Officers of their duties as officers of the Funds.
Such participation, if addressed in conformity with the provisions of the 1940
Act and the Advisers Act, will be deemed to have been handled ethically. In
addition, it is recognized by the Boards that the Covered Officers may also be
officers or employees of one or more other investment companies advised by the
Advisor and covered by this or other Codes.

      Other conflicts of interest are covered by the Code, even if such
conflicts of interest are not subject to provisions in the 1940 Act and the
Advisers Act. In reading the following examples of conflicts of interest under
the Code, the Covered Officers should keep in mind that such a list cannot be
exhaustive by covering every possible scenario. It follows that the overarching
principle--that the personal interest of a Covered Officer should not be placed
improperly before the interest of a Fund--should be the guiding principle in all
circumstances.

      Each Covered Officer must:

      -     avoid conflicts of interest whenever possible;

      -     handle any actual or apparent conflict of interest ethically;

      -     not use his personal influence or personal relationships improperly
            to influence investment decisions or financial reporting by the
            Funds whereby the Covered Officer would benefit personally to the
            detriment of the Funds;

                                        2
<Page>

      -     not cause the Funds to take action, or fail to take action, for the
            individual personal benefit of the Covered Officer rather than for
            the benefit of the Funds;

      -     not use material, non-public knowledge of portfolio transactions
            made or contemplated for the Funds to profit personally, or to cause
            others to profit, by the market effect of such transactions; and

      -     as described in more detail below, discuss any material transaction
            or relationship, which could reasonably be expected to give rise to
            a conflict of interest, with Rex A. Sinquefield, the Funds'
            Co-Chairman (the "Designated Ethics Officer"). In the event Mr.
            Sinquefield is not available, the Chairman of the Audit Committee
            may take action required hereunder of the Designated Ethics Officer.

      There are some conflict of interest situations that should always be
discussed with the Designated Ethics Officer, if material. Examples of these
situations include:

      -     any outside business activity that detracts from an individual's
            ability to devote appropriate time and attention to his
            responsibilities with the Funds;

      -     service as a director on the board of any public or private company;

      -     the receipt of any non-nominal gifts;

      -     the receipt of any entertainment from any company with which the
            Funds have current or prospective business dealings, unless such
            entertainment is business-related, reasonable in cost, appropriate
            as to time and place, and not so frequent as to raise any question
            of impropriety;

      -     being in the position of supervising, reviewing or having any
            influence on the job evaluation, pay or benefit of any immediate
            family member;

      -     any ownership interest in, or any consulting or employment
            relationship with, any of the Funds' service providers, other than
            the Advisor and DFA Securities Inc. ("DFAS"), or any affiliated
            person thereof; and

      -     a direct or indirect financial interest in commissions, transaction
            charges or spreads paid by a Fund for effecting portfolio
            transactions or for selling or redeeming shares other than an
            interest arising from the Covered Officer's employment, such as
            compensation or equity ownership.

IV.   DISCLOSURE

      Each Covered Officer is required to be familiar and comply with the Funds'
disclosure controls and procedures so that the Funds' subject reports and
documents filed with the SEC comply in all material respects with the applicable
federal securities laws and SEC rules. In addition, each Covered Officer having
direct or supervisory authority regarding these SEC filings or the Funds' other
public communications should, to the extent appropriate within his area of
responsibility, consult with other Fund officers and employees and take other
appropriate steps regarding these disclosures with the goal of making full,
fair, accurate, timely and understandable disclosure.

      Each Covered Officer:

                                        3
<Page>

      -     must familiarize himself with the disclosure requirements applicable
            to the Funds as well as the business and financial operations of the
            Funds; and

      -     must not knowingly misrepresent, or intentionally cause others to
            misrepresent, facts about the Funds to others, whether within or
            outside the Funds, including to the Funds' directors/trustees and
            auditors, and to governmental regulators and self-regulatory
            organizations.

V.    COMPLIANCE

      It is the Funds' policy to comply with all applicable laws and
governmental rules and regulations. It is the responsibility of each Covered
Officer to adhere to the standards and restrictions imposed by those laws, rules
and regulations, including those relating to affiliated transactions, accounting
and auditing matters.

VI.   REPORTING AND ACCOUNTABILITY

      Each Covered Officer must:

      -     upon adoption of the Code, affirm in writing to the Designated
            Ethics Officer that he has received, read, and understands the Code;

      -     annually thereafter affirm to the Designated Ethics Officer that he
            has received, read and understands the Code and has complied with
            the requirements of the Code;

      -     not retaliate against any employee or Covered Officer for reports of
            potential violations that are made in good faith; and

      -     notify the Designated Ethics Officer promptly if the Covered Officer
            knows of any violation of this Code. Failure to do so is itself a
            violation of this Code.

      The Designated Ethics Officer is responsible for applying the provisions
of the Code to specific situations in which questions arise under the Code, and
the Designated Ethics Officer has the authority to interpret this Code in any
particular situation. The Designated Ethics Officer is authorized (and
encouraged) to consult, as appropriate, with the Audit Committee of the Funds,
the members of the Boards who are not "interested persons" (together, the
"Independent Directors"), and counsel to the Funds and the Independent
Directors.

      The Funds will comply with the following procedures in investigating and
enforcing this Code:

      -     the Designated Ethics Officer will take all appropriate action to
            investigate any violations and potential violations reported to him;

      -     violations and potential violations will be reported to the Audit
            Committee after such investigation;

      -     if the Audit Committee determines that a violation of this Code has
            occurred, the Audit Committee will consider appropriate action,
            which may include the review of, and necessary modifications to,
            applicable policies and procedures; notification to appropriate
            personnel of the Advisor or the Advisor's board of directors; or
            recommending the dismissal of the Covered Officer;

                                        4
<Page>

      -     appropriate disciplinary or preventive action may include a letter
            of censure, suspension, dismissal or, in the event of criminal or
            other serious violations of law, notification of the SEC or other
            appropriate law enforcement authorities;

      -     the Audit Committee will report to the Boards any action (whether
            disciplinary, preventive or otherwise) taken to address violations
            of this Code;

      -     the Audit Committee will be responsible for granting waivers and
            determining sanctions, as appropriate; and

      -     any changes to or waivers of this Code will, to the extent required,
            be disclosed on Form N-CSR as provided by SEC rules.

VII.  OTHER POLICIES AND PROCEDURES

      The code of ethics under Rule 17j-1 under the 1940 Act, adopted by the
Funds, the Advisor and the affiliated companies of the Advisor, and the
Advisor's policies and procedures set forth in the STATEMENT OF POLICY OF
EMPLOYEE TRADING are separate requirements applying to the Covered Officers and
others, and are not part of this Code.

VIII. AMENDMENTS

      This Code may not be amended except in written form, which is specifically
approved or ratified by a majority vote of the Boards, including a majority of
the Independent Directors.

IX.   CONFIDENTIALITY

      All reports and records prepared or maintained pursuant to this Code shall
be considered confidential and shall be maintained and protected accordingly.
Except as otherwise required by law or this Code, such matters shall not be
disclosed to anyone other than the members of the Boards and their counsel, the
Funds, and the Advisor.

X.    INTERNAL USE

      The Code is intended solely for the internal use by the Funds and does not
constitute an admission, by or on behalf of any Fund, as to any fact,
circumstance, or legal conclusion.


Date: June 26, 2003

                                        5
<Page>

                                                                       EXHIBIT A

                 PERSONS COVERED BY THIS CODE OF BUSINESS ETHICS

            David G. Booth (Principal Executive Officer of the Funds)

         Michael T. Scardina (Principal Financial Officer of the Funds)

                                       A-1