Document:

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                                                                     EXHIBIT 4.3

                       ASSIGNMENT AND ASSUMPTION AGREEMENT

      This ASSIGNMENT AND ASSUMPTION AGREEMENT, dated as of [March] ___, 2002
(this "Agreement"), is entered into by and between Mobile Storage Group, Inc., a
California corporation ("Assignor"), and Mobile Services Group, Inc., a
California corporation ("Assignee"). Unless otherwise defined herein,
capitalized terms used herein shall have the meanings ascribed thereto in the
Shareholders Agreement (defined below).

                              W I T N E S S E T H:

      WHEREAS, Assignor and certain of its shareholders have entered into that
certain Shareholders Agreement, dated as of April 4, 2001 (as amended, restated
or otherwise modified through the date hereof, the "Shareholders Agreement");

      WHEREAS, Assignor and Assignee are parties to that certain Agreement and
Plan of Merger [being executed concurrently herewith] (the "Agreement of
Merger") pursuant to which Assignor will be merged with a wholly owned
subsidiary of Assignee (the "Merger"), with Assignor as the surviving
corporation in the Merger;

      WHEREAS, after the completion of the Merger, Assignor will be a wholly
owned subsidiary of Assignee;

      WHEREAS, in connection with the Merger and pursuant to Section 14.10(a) of
the Shareholders Agreement, Assignor desires to assign, transfer and convey all
of its rights, titles, interests, privileges, benefits and remedies in, to and
under the Shareholders Agreement to Assignee; and

      WHEREAS, in connection with the Merger, Assignee has agreed to assume all
of the obligations or duties of Assignor under the Shareholders Agreement.

      NOW, THEREFORE, the undersigned, in consideration of the premises,
covenants and agreements contained herein, do hereby agree as follows:

      Section 1. Assignment. In consideration for Assignee assuming all of the
obligations or duties of Assignor pursuant to the Agreement of Merger and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, Assignor hereby assigns, conveys and transfers to Assignee
all of Assignor's rights, titles, interests, privileges, benefits and remedies
in, to and under the Shareholders Agreement.

      Section 2. Assumption. Assignee hereby accepts the assignment, conveyance
and transfer of all of Assignor's obligations or duties under the Shareholders
Agreement.

      Section 3. Effective Time of this Agreement. This Agreement shall become
operative (the "Effective Time") only when the Merger shall have become
effective in accordance with the terms of the Agreement of Merger.

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      Section 4. Definition of "Company". Each of Assignor and Assignee agrees
that that the definition of "Company" contained in Section 1.1(j) of the
Shareholders Agreement shall be amended, without any further action, from and
after the Effective Time to mean "Mobile Services Group, Inc., and any successor
or assign thereof."

      Section 5. Future Cooperation. Each of Assignor and Assignee hereby agrees
to cooperate, with the other or with any person, at all times from and after the
date hereof with respect to all of the matters described herein, and to execute,
acknowledge and deliver such further assignments, transfers, conveyances,
assurances, releases, acceptances, amendments, notifications and other documents
as may be reasonably requested for the purpose of giving effect to, evidencing
or giving notice of the transactions contemplated by this Agreement.

      Section 6. Successor and Assigns. This Agreement shall be binding upon and
inure to the benefit of each of the parties hereto and their respective
successors and assigns.

      Section 7. Governing Law. This Agreement shall be governed by, and
construed in accordance with, the laws of the State of California without regard
to any applicable principles of conflicts of law.

      Section 8. Counterparts. This Agreement may be executed in separate
counterparts, each of which when so executed and delivered shall be an original
for all purposes, but all such counterparts shall constitute but one and the
same instrument.

      Section 9. Severability. Any provision of this Agreement that is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

      Section 10. Headings. This section and article headings contained herein
are for convenience only and shall not be construed as part of this Agreement.

                            [Signature Page Follows]

                                        2
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      IN WITNESS WHEREOF, Assignor and Assignee have executed this Agreement as
of the date first above written.

                                          MOBILE STORAGE GROUP, INC., a
                                          California corporation, as Assignor

                                          By: __________________________________
                                              Name:
                                              Title:

                                          MOBILE SERVICES GROUP, INC., a
                                          California corporation, as Assignee

                                          By: __________________________________
                                              Name:
                                              Title:

Each of the undersigned hereby consents to the assignment by Assignor of the
Shareholders Agreement to the Assignee in the manner provided for in this
Agreement, and agrees to amend the Shareholders Agreement in the manner
described in Section 4 of this Agreement. The following consent and agreement
may be executed in separate counterparts.

WINDWARD CAPITAL PARTNERS II, L.P., a
Delaware limited partnership, as the Windward Agent

By: WINDWARD CAPITAL GP II, LLC, a
    Delaware limited liability company, its General Partner

    ----------------------------------
    Name:
    Title:

                                       3
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MAJORITY ROLL-OVER SHAREHOLDERS:

ROBERTSON LIVING TRUST dated 3/7/00

By: __________________________________
    Name:
    Title:

ZERO-SUM INVESTMENTS S.A.

By: __________________________________
    Name:
    Title:

                                       4<PAGE>
                                                                     EXHIBIT 4.4

                          SHAREHOLDER AGREEMENT JOINDER

            This SHAREHOLDER AGREEMENT JOINDER, dated as of November 13, 2001
(this "Joinder"), is entered into between MOBILE STORAGE GROUP, INC., a
California corporation (the "Company"), and WINDWARD/MSG CO-INVEST II, LLC, a
Delaware limited liability company ("WCI II").

                                   WITNESSETH

            WHEREAS, reference is made to that certain Shareholders Agreement,
dated as of April 4, 2000, as amended pursuant to that certain Amendment No. 1
to Shareholders Agreement dated as of November 13, 2001 (as further amended,
restated, supplemented or otherwise modified from time to time, the
"Shareholders Agreement"; terms used herein and not otherwise defined have the
meanings assigned to them in the Shareholders Agreement), by and among certain
shareholders of the Company named therein (the "Existing Shareholders") and the
Company;

            WHEREAS, in connection with that certain Stock and Unit Purchase
Agreement, dated as of November 13, 2001, among the Company, WCI II and the
other purchasers named therein, WCI II will acquire shares of the Company's
common stock;

            WHEREAS, it is a condition precedent to the transfer of such shares
to WCI II that WCI II enter into this Joinder, whereby it will agree to be bound
(to the same extent as contemplated under the Shareholders Agreement with
respect to the Existing Shareholders) by the terms and conditions of the
Shareholders Agreement, and to be deemed a Shareholder and a member of the
Windward Group, with the same rights and obligations as a Shareholder and a
member of the Windward Group for all purposes thereunder;

            NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

                                     JOINDER

            WCI II hereby agrees that, in accordance with Article X of the
Shareholders Agreement and upon its acquisition of the Company's common stock
shares, it is bound under and joins the Shareholders Agreement as if it were an
original party thereto, with all the rights and obligations thereunder as
applied to members of the Windward Group and Existing Shareholders.

            The Company hereby acknowledges WCI II's agreement to be bound under
the Shareholders Agreement and that it is entitled to all rights and benefits
available to a member of the Windward Group or a Shareholder thereunder and that
WCI II shall be deemed to be, for all purposes under the Shareholders Agreement,
a "Shareholder" and a member of the "Windward Group". The Company further
acknowledges that, under Section 10.3 of the Shareholders Agreement, the
effectiveness of this Joinder is not dependent on obtaining the consent of any
of the Existing Shareholders.

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            IN WITNESS WHEREOF, the parties hereto have caused this Joinder to
be executed by their duly authorized representatives as of the date first
written above.

                                      WINDWARD/MSG CO-INVEST II, LLC, a Delaware
                                      limited liability company

                                      By:  WINDWARD CAPITAL GP II, LLC, a
                                           Delaware limited liability company,
                                           its Manager

                                           By:   /s/ PETER SCOTT MACDONALD
                                                --------------------------------
                                                Name:  Peter Scott Macdonald
                                                Title: Managing Member

ACKNOWLEDGED AND AGREED:

MOBILE STORAGE GROUP, INC.

By:   /s/ RON F. VALENTA
     --------------------------------
     Name:  Ron F. Valenta
     Title: President

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