<PAGE>
                                                                   EXHIBIT 10.18
 
                             SHAREHOLDERS AGREEMENT
 
    This shareholders agreement (this "Agreement") is made as of February 11,
1997 by and among PREFERRED EMPLOYERS HOLDINGS, INC., having an address at 10800
Biscayne Boulevard, 10th Floor, Miami, Florida 33161 (together with Preferred
Employers Group, being the predecessor and a wholly-owned subsidiary of
Preferred Employers Holdings, Inc., the "Company"), MEL HARRIS, an individual
having an address at 10800 Biscayne Boulevard, Penthouse, Miami, Florida 33161
("Harris") and HOWARD ODZER, an individual having an address at 1399 Northeast
103rd Street, Miami Shores, Florida 33138 ("Odzer" and, together with Harris,
the "Shareholders").
 
                                   WITNESSETH
 
    WHEREAS, the Company and the Shareholders were parties to that certain
Amended and Restated Shareholders Agreement dated as of May 15, 1995 (the
"Original Shareholders Agreement"; capitalized terms not otherwise defined
herein shall have the meanings assigned thereto in the Original Shareholders
Agreement);
 
    WHEREAS, the Company completed an initial public offering of its stock under
the Securities Act of 1933, as amended, pursuant to a prospectus dated February
5, 1997 (the "Offering");
 
    WHEREAS, pursuant to the terms of the Original Shareholders Agreement, such
Agreement terminated immediately prior to completion of the Offering;
 
    WHEREAS, the Company and the Shareholders desire to enter into this
Shareholders Agreement pursuant to Section 17(b) of the Original Shareholders
Agreement.
 
    NOW, THEREFORE, in consideration of the mutual covenants and agreements set
forth herein and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:
 
    1.  INDEMNIFICATION.  (a) Each Shareholder (including here and hereinafter,
the heirs, executors, administrators or estate of such Shareholder) who is or
was a director, officer, agent or employee of the Company or who is or was
serving at the request of the Company in the position of a director, officer,
trustee, partner, agent or employee of another corporation, partnership, joint
venture, trust or other enterprise, shall be indemnified by the Company as of
right to the fullest extent permitted or authorized by current or future
legislation or by current or future judicial or administrative decision (but, in
the case of any future legislation or decision, only to the extent that it
permits the Company to provide broader indemnification rights than permitted
prior to the legislation or decision), against all fines, liabilities,
settlements, costs and expenses, including attorneys' fees, asserted against him
or incurred by him (whether arising out of actions or omissions occurring before
or after the date hereof) in his capacity as such director, officer, trustee,
partner, agent or employee, or arising out of his status as such director,
officer, trustee, partner, agent or employee. The foregoing right of
indemnification shall not be exclusive of other rights to which those seeking
indemnification may be entitled.
 
    (b) Subject to the provisions of Section 1(c) hereof, costs, charges and
expenses (including reasonable attorneys' fees) incurred by a person referred to
in Section 1(a) hereof in defending a civil or criminal suit, action or
proceeding shall be paid promptly by the Company, as statements therefor are
received, in advance of the final disposition thereof, upon receipt of an
undertaking to repay all amounts advanced if it is ultimately determined that
the person is not entitled to be indemnified by the Company as authorized by
this Section 1.
 
    (c) Promptly after a Shareholder (or his heirs, executors, administrators
and estate) (collectively, an "Indemnified Person") receives notice of the
commencement of any action or other proceeding in respect of which
indemnification or reimbursement may be sought under this Section 1, such
Indemnified Person will notify the Company thereof; but the omission so to
notify the Company shall not relieve the Company from any obligation under this
Section 1 unless, and only to the extent that, such omission results in
prejudice to the rights and interests of the Company. If any such action or
other proceeding shall be
 
                                       1
<PAGE>
brought against any Indemnified Person, the Company shall, upon written notice
given reasonably promptly following the Indemnified Person's notice to the
Company of such action or proceeding, be entitled to assume the defense thereof
at the Company's expense with counsel chosen by the Company, provided, however,
that any Indemnified Person may at his own expense retain separate counsel to
participate in such defense. Notwithstanding the foregoing, such Indemnified
Person shall have the right to employ separate counsel at the Company's expense
and to control his own defense of such action or proceeding if (i) the Company
has failed promptly to assume the defense, or (ii) in the reasonable opinion of
counsel to the Company, there is a conflict of interest arising from the fact
that the same counsel is representing both the Company and the Indemnified
Person or there is a potential conflict of interest between the Company and such
Indemnified Person that would make such separate representation advisable. The
Company will not, without the prior written consent of the Indemnified Person,
settle, compromise or consent to the entry of any judgment in or otherwise seek
to terminate any pending or threatened claim, action or proceeding in respect of
which indemnification or reimbursement may be sought under this Section 1
(whether or not the Indemnified Person is a party thereto) unless such
settlement, compromise, consent or termination includes an unconditional release
of the Indemnified Person from all liability arising or that may arise out of
such claim, action or proceeding.
 
    (d) If this Section 1 or any portion of it is invalidated on any ground by a
court of competent jurisdiction, the Company shall nevertheless indemnify each
Shareholder (and his heirs, executors, administrators and estate) to the fullest
extent permitted by all portions of this Section 1 that has not been invalidated
and to the fullest extent permitted by law.
 
    (e) This Section 1 is intended for the benefit of, and shall be enforceable
by, the Shareholders (and the heirs, executors, administrators and estate of
such persons) and shall be binding on the Company and its respective successors
and assigns.
 
    2.  REGISTRATION RIGHTS; TAG-ALONG RIGHTS.  The Company agrees that Odzer
(and/or members of Odzer's family or any entity owned by Odzer or Odzer's
family) shall be granted registration rights (including with respect to those
shares held in escrow pursuant to that certain Share Escrow Agreement dated
February 5, 1997, once such shares have been released from escrow) PARI PASSU
with those granted to Harris (and/or members of Harris' family), if any, pro
rata based on the number of shares of Stock owned by them at the time any such
rights are granted. In the event Harris (or members of Harris' family) proposes
to transfer any shares of Stock, to a bona fide third party purchaser, Harris
shall offer Odzer (and/or members of Odzer's family or any entity owned by Odzer
or Odzer's family) the right to participate in such transfer on a pro rata
basis, at the same price and upon identical terms and conditions, as such
proposed transfer by Harris.
 
    3.  RIGHT OF FIRST REFUSAL.  (a) A Shareholder (the "Offering Shareholder")
who proposes to dispose of any shares of Stock shall give a notice (the
"Notice") signed by the offering Shareholder to the Company and on the same day
give Notice to the other Shareholder (the "Non-Offering Shareholder") of such
Offering Shareholder's proposed disposition; PROVIDED, HOWEVER, that no Notice
of any proposed disposition by sale of the offered Shares shall be valid unless
the Offering Shareholder shall have received prior to the date of the Notice an
offer therefor in writing from any BONA FIDE purchaser stating the price, terms,
and conditions of the proposed sale. The Notice shall specify the number of
shares (the "Offered Shares") the Offering Shareholder intends to dispose of,
identify and give the address of the person to whom the Offering Shareholder
proposes to dispose of the Offered Shares, and indicate the price, terms, and
conditions of the proposed disposition. The Company shall have the irrevocable
and exclusive first option, but not the obligation, to purchase all, but not
part, of the Offered Shares, at the price and upon any terms and conditions
equal to those offered by the prospective purchaser, provided that the Company
gives notice of its election to purchase the Offered Shares to the Offering
Shareholder within 30 days after the Company receives the Notice.
 
    (b) If the Company does not elect to purchase all of the Offered Shares as
provided in Section 3(a) above, then the Offering Shareholders shall thereafter
provide the Non-Offering Shareholder with a notice (the "Second Notice") that
the Company has not so elected, and the Non-Offering Shareholder
 
                                       2
<PAGE>
shall have the irrevocable and exclusive second option, but not the obligation,
to purchase all, but not part, of the Offered Shares, at the price and upon such
terms and conditions as those offered by the prospective purchaser. If the
Non-Offering Shareholder elects to purchase the Offered Shares he shall give
notice of such election to the Offering Shareholder within 10 days after the
receipt of the Second Notice by the Non-Offering Shareholder and the purchase
thereof shall be closed within 40 days after receipt of the Second Notice.
 
    (c) If an Offering Shareholder gives the required Notice, and the Second
Notice, and the Company and the Non-Offering Shareholder do not elect, pursuant
to Sections 3(a) and 3(b) , to purchase the Offered Shares, the Offering
Shareholder may dispose of the Offered Shares to the person or persons, at the
price, and on the terms and conditions specified in the Notice, provided that
each such person acquiring the Offered Shares becomes a party to this Agreement
upon such acquisition, and any shares not so disposed of by such Offering
Shareholder may not thereafter be disposed of, except in compliance with the
terms and conditions of this Agreement.
 
    (d) The provisions of Section 3 shall remain in effect for so long as Odzer
owns more than fifteen percent (15%) of the outstanding Stock of the Company.
Furthermore, the Proxy given as of May 15, 1995 shall continue irrevocable for
so long as this Section 3 remains in full force and effect.
 
    (e) The provisions of Section 3 shall not apply to (i) any proposed
dispositions to be made pursuant to Rule 144 or any Registration Statement in
effect under the Securities Act of 1933, as amended, or (ii) any transfers by a
Shareholder of shares of Stock or beneficial interests therein to their
respective spouses, or other immediate family members, or to a trust or other
entity for the sole benefit of any of the foregoing; provided that any such
transferee agrees to be bound by the terms of this Agreement.
 
    4.  NOTICES.  Any notice or other communication required or permitted to be
given hereunder shall be in writing and shall be mailed by certified mail,
return receipt requested, or delivered against receipt to the party to whom it
is to be given at the address of such party set forth below (or to such other
address as the party shall have furnished in writing in accordance with the
provisions of this Section 4):
 
<TABLE>
<S>                             <C>
Mr. Harris:                     10800 Biscayne Boulevard, Penthouse
                                Miami, Florida 33161
 
            with a copy (which copy shall not constitute notice) to:
 
                                Donald J. Bezahler, Esq.
                                Baer Marks & Upham LLP
                                805 Third Avenue, 20th Floor
                                New York, New York 10022-7513
 
Mr. Odzer:                      1399 Northeast 103rd Street
                                Miami Shores, Florida 33138
 
            with a copy (which copy shall not constitute notice) to:
 
                                Thomas R. McGuigan, P.A.
                                Steel Hector & Davis
                                200 South Biscayne Blvd., 40th Floor
                                Miami, Florida 33131-2398
 
The Company:                    10800 Biscayne Boulevard, 10th Floor
                                Miami, Florida 33161
 
            with a copy (which copy shall not constitute notice) to:
 
                                Donald J. Bezahler, Esq.
                                Baer Marks & Upham LLP
                                805 Third Avenue, 20th Floor
                                New York, New York 10022-7513
</TABLE>
 
                                       3
<PAGE>
    Notice to the estate of any party shall be sufficient if addressed to the
party as provided in this Section 4. Any notice or other communication given by
certified mail shall be deemed given at the time of certification thereof,
except for a notice changing a party's address which shall be deemed given at
the time of receipt thereof.
 
    5.  MISCELLANEOUS.  (a) This Agreement may be amended at any time and from
time to time by unanimous written agreement of the Shareholders.
 
    (b) This Agreement and the rights of the parties hereunder shall be governed
by, and construed in accordance with, the laws of the state of Florida, without
giving effect to rules governing conflicts of law.
 
    (c) This Agreement and the rights and obligations hereunder, may not be
assigned and any such assignment shall be void and null. Except as otherwise
specifically provided herein, this Agreement shall be binding upon and inure to
the benefit of the parties and their legal representatives, heirs,
administrators, executors, and successors.
 
    (d) Captions and section headings contained in this Agreement are inserted
only as a matter of convenience and in no way define, limit, or extend the scope
or intent of this Agreement or any provision hereof.
 
    (e) If any provision of this Agreement or the application of any provision
to any person or circumstance shall be held invalid, the remainder of this
Agreement, or the application of that provision to persons or circumstances
other than those to which it is held invalid, shall not be affected thereby.
 
    (f) This Agreement may be executed in several counterparts, each of which
shall be deemed an original but all of which shall constitute one and the same
instrument.
 
    (g) Except as otherwise set forth in this Agreement, including in Section
3(d) hereof, the provisions of this Agreement shall remain in effect for six (6)
years after Odzer last serves as a director, officer, agent or employee of the
Company, or at the request of the Company, serves as a director, officer,
trustee, partner, agent or employee of another corporation, partnership, joint
venture, trust or other enterprise.
 
    6.  ARBITRATION.  (a) Any dispute or controversy arising out of or relating
to this Agreement, any document or instrument delivered pursuant to, in
connection with, or simultaneously with this Agreement, or any breach of this
Agreement or any such document or instrument shall be settled by arbitration to
be held in the County of Dade, State of Florida in accordance with the
Commercial Arbitration Rules then in effect of the American Arbitration
Association or any successor thereto, and judgment upon the award rendered by
the Arbitrator(s) may be entered in any Court having jurisdiction thereof. The
Arbitrator(s) may grant injunctions or other relief in such dispute or
controversy. The costs and expenses of such arbitration shall be assumed as
determined by the Arbitrator(s), and each party shall separately pay his own
attorneys' fees and expenses.
 
    (b) Section 6 shall remain in effect for at least six (6) years after Odzer
last serves as a director, officer, agent or employee of the Company, or at the
request of the Company, serves as a director, officer, trustee, partner, agent
or employee of another corporation, partnership, joint venture, trust or other
enterprise.
 
    (c) Notwithstanding anything contained herein to the contrary, any dispute
or controversy arising out of or relating to this Agreement with respect to
federal securities laws shall not be subject to arbitration as provided by this
Section 6.
 
                                       4
<PAGE>
    IN WITNESS WHEREOF,  the undersigned have executed this Agreement as of the
11th day of February, 1997.
 
<TABLE>
<S>                                       <C>        <C>        <C>
                                          /s/ HOWARD ODZER
                                          -------------------------------------------------
                                          Howard Odzer
 
                                          /s/ MEL HARRIS
                                          -------------------------------------------------
                                          Mel Harris
 
                                          PREFERRED EMPLOYERS HOLDINGS, INC.
                                          By:        /s/ MEL HARRIS
                                                     ---------------------------------------------
                                                     Name:      Mel Harris
                                                     Title:     Chairman of the Board and
                                                                Chief Executive Officer
</TABLE>
 
                                       5