<PAGE>

    As filed with the Securities and Exchange Commission on August 10, 2001.
                                                          Registration No. 333-


                       SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C.  20549

                            ________________________

                                    FORM S-8
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933
                            ACT MANUFACTURING, INC.
             (Exact name of registrant as specified in its charter)

<TABLE>
<CAPTION>
<S>                                                               <C>
               MASSACHUSETTS                                                  04-2777507
(State or other jurisdiction of incorporation or organization)     (I.R.S. Employer Identification No.)
</TABLE>

                                  2 CABOT ROAD
                          HUDSON, MASSACHUSETTS 01749
                                 (978) 567-4000
              (Address of Principal Executive Offices)  (Zip Code)
                      ____________________________________

                  SECOND AMENDED AND RESTATED 1995 STOCK PLAN

                            (Full title of the plan)
                      ____________________________________

                                  JOHN A. PINO
                     PRESIDENT, CHIEF EXECUTIVE OFFICER AND
                             CHAIRMAN OF THE BOARD
                            ACT MANUFACTURING, INC.
                                  2 CABOT ROAD
                          HUDSON, MASSACHUSETTS  01749
                                 (978) 567-4000
           (Name and address including zip code and telephone number,
                   including area code, of agent for service)
                      ____________________________________

                                    Copy to:
                             JOHN A. MELTAUS, ESQ.
                        TESTA, HURWITZ & THIBEAULT, LLP
                                125 HIGH STREET
                          BOSTON, MASSACHUSETTS  02110
                                 (617) 248-7000

     Approximate date of commencement of proposed sale to the public: As soon as
practicable after this Registration Statement becomes effective.
                  ____________________________________________


                        CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
                                                     Proposed                Proposed
                                                     Maximum                  Maximum
       Title of                Amount                Offering                Aggregate            Amount of
    Securities to              to be                Price Per                Offering            Registration
    be Registered            Registered               Share                    Price                 Fee
---------------------------------------------------------------------------------------------------------------
<S>                          <C>                  <C>                         <C>                  <C>
SECOND AMENDED AND
RESTATED 1995 STOCK
PLAN
Common Stock                 1,000,000              $9.93(1)                   $9,930,000.00         $2,482.50
(par value $.01 per
share)
</TABLE>

(1)  The exercise price of options issued pursuant to the Second Amended and
     Restated 1995 Stock Plan is determined at the time of grant.  None of the
     shares being registered hereunder is subject to any outstanding options.
     Accordingly, the proposed maximum offering price of $9.93 per share,
     which is the average of the high and low prices of the common stock of the
     registrant reported on the Nasdaq National Market on August 9, 2001, is
     set forth solely for purposes of calculating the filing fee pursuant to
     Rule 457(c) and (h).
<PAGE>

                                      -1-

     This Registration Statement registers 1,000,000 additional shares of the
Registrant's Common Stock issuable upon exercise of options issued pursuant to
the Registrant's Second Amended and Restated 1995 Stock Plan.


                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS


Item 1.  Plan Information.
         ----------------

     The documents containing the information specified in this Item 1 will be
sent or given to employees, directors or others as specified by Rule 428(b)(1).
In accordance with the rules and regulations of the Securities and Exchange
Commission (the "Commission") and the instructions to Form S-8, such documents
are not being filed with the Commission either as part of this Registration
Statement or as prospectuses or prospectus supplements pursuant to Rule 424.

Item 2.  Registrant Information and Employee Plan Annual Information.
         -----------------------------------------------------------

     The documents containing the information specified in this Item 2 will be
sent or given to employees as specified by Rule 428(b)(1).  In accordance with
the rules and regulations of the Commission and the instructions to Form S-8,
such documents are not being filed with the Commission either as part of this
Registration Statement or as prospectuses or prospectus supplements pursuant to
Rule 424.


                                    PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT


Item 3.  Incorporation of Documents by Reference.
         ---------------------------------------

     The following documents filed with the Commission are incorporated by
reference in this Registration Statement:

     (a)  Registrant's Annual Report on Form 10-K for the fiscal year ended
          December 31, 2000.

     (b)  Registrant's Quarterly Report on Form 10-Q for the period ended March
          31, 2001.

     (c)  All other reports filed pursuant to Section 13(a) or 15(d) of the
          Securities Exchange Act of 1934, as amended (the "Exchange Act"),
          since the end of the fiscal year ended December 31, 2000.

     (d)  The section entitled "Description of Registrant's Securities to be
          Registered," contained in the Registrant's Registration Statement on
          Form 8-A, filed on February 15, 1995 pursuant to Section 12(g) of the
          Exchange Act.

<PAGE>

                                      -2-

     All documents subsequently filed with the Commission by the Registrant
pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act, prior to
the filing of a post-effective amendment which indicates that all securities
offered herein have been sold or which deregisters all securities then remaining
unsold, shall be deemed to be incorporated by reference in this Registration
Statement and to be a part hereof from the date of filing of such documents.

Item 4.  Description of Securities.
         -------------------------

     Not applicable.

Item 5.  Interest of Named Experts and Counsel.
         -------------------------------------

     Not applicable.

Item 6.  Indemnification of Directors and Officers.
         -----------------------------------------

     Section 67 of Chapter 156B of the Massachusetts General Laws provides that
a corporation may indemnify its directors and officers to the extent specified
in or authorized by (i) the articles of organization, (ii) a by-law adopted by
the stockholders, or (iii) a vote adopted by the holders of a majority of the
shares of stock entitled to vote on the election of directors.  In all
instances, the extent to which a corporation provides indemnification to its
directors and officers under Section 67 is optional.  In its Amended and
Restated By-Laws, the Registrant has elected to commit to provide
indemnification to its directors and officers in specified circumstances.
Generally, Article V, Section 2 of the Registrant's Amended and Restated By-Laws
indemnifies directors and officers of the Registrant against liabilities and
expenses arising out of legal proceedings brought against them by reason of
their status as directors or officers or by reason of their agreeing to serve,
at the request of the Registrant, as a director or officer with another
organization.  Under this provision, a director or officer of the Registrant
shall be indemnified by the Registrant for all costs and expenses  (including
attorneys' fees), judgments, liabilities and amounts paid in settlement of such
proceedings, even if he is not successful on the merits, if he acted in good
faith in the reasonable belief that his action was in the best interests of the
Registrant.  The Registrant's Board of Directors may authorize advancing
litigation expenses to a director or officer at his request upon receipt of an
undertaking by any such director or officer to repay such expenses if it is
ultimately determined that he is not entitled to indemnification for such
expenses.

     Article 6 of the Registrant's Second Restated Articles of Organization, as
amended, eliminates the personal liability of the Registrant's directors to the
Registrant or its stockholders for monetary damages for breach of a director's
fiduciary duty, except to the extent Chapter 156B of the Massachusetts General
Laws prohibits the elimination or limitation of such liability.

     The Registrant maintains directors' and officers' liability insurance for
the benefit of its directors and certain of its officers.

Item 7.  Exemption from Registration Claimed.
         -----------------------------------

     Not applicable.

<PAGE>

                                      -3-

Item 8.  Exhibits.
         --------

     Exhibit No.    Description of Exhibit
     -----------    ----------------------

     Exhibit 4.1    Second Restated Articles of Organization of the Registrant
                    (filed as Exhibit 3.1 to the Registrant's Annual Report on
                    Form 10-K for the year ended December 31, 1995, and
                    incorporated herein by reference).

     Exhibit 4.2    Articles of Amendment to the Second Restated Articles of
                    Organization of the Registrant (filed as Exhibit 4.2 to the
                    Registrant's Registration Statement on Form S-8, File No.
                    333-84231, and incorporated herein by reference).

     Exhibit 4.3    Amended and Restated By-Laws of the Registrant, as amended
                    (filed as Exhibit 3.2 to the Registrant's Registration
                    Statement on Form S-1, File No. 33-89532, and incorporated
                    herein by reference).

     Exhibit 4.4    Specimen certificate representing the Common Stock of the
                    Registrant (filed as Exhibit 4.1 to the Registrant's
                    Registration Statement on Form S-1, File No. 33-89532, and
                    incorporated herein by reference).

     Exhibit 4.5    Second Amended and Restated 1995 Stock Plan.

     Exhibit 5.1    Opinion of Testa, Hurwitz & Thibeault, LLP.

     Exhibit 23.1   Consent of Testa, Hurwitz & Thibeault, LLP (contained in
                    Exhibit 5.1).

     Exhibit 23.2   Consent of Deloitte & Touche LLP.

     Exhibit 24.1   Power of Attorney (included as part of the signature page to
                    this Registration Statement).

Item 9.  Undertakings.
         ------------

     (a) The undersigned Registrant hereby undertakes:

          (1)  To file, during any period in which offers or sales are being
               made, a post-effective amendment to this Registration Statement:

               (i)   To include any prospectus required by Section 10(a)(3) of
                     the Securities Act of 1933;

               (ii)  To reflect in the prospectus any facts or events arising
                     after the effective date of the Registration Statement (or
                     the most recent post-effective amendment thereof) which,
                     individually or in the aggregate, represent a fundamental
                     change in the information set forth in the Registration
                     Statement;

<PAGE>

                                      -4-

               (iii) To include any material information with respect to the
                     plan of distribution not previously disclosed in the
                     Registration Statement or any material change to such
                     information in the Registration Statement;

                     provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii)
                     do not apply if the information required to be included in
                     a post-effective amendment by those paragraphs is contained
                     in periodic reports filed with or furnished to the
                     Commission by the Registrant pursuant to Section 13 or
                     Section 15(d) of the Securities Exchange Act of 1934 that
                     are incorporated by reference in the Registration
                     Statement.

          (2)  That, for the purpose of determining any liability under the
               Securities Act of 1933, each such post-effective amendment shall
               be deemed to be a new Registration Statement relating to the
               securities offered therein, and the offering of such securities
               at that time shall be deemed to be the initial bona fide offering
               thereof.

          (3)  To remove from registration by means of a post-effective
               amendment any of the securities being registered which remain
               unsold at the termination of the offering.

     (b)  The undersigned Registrant hereby undertakes that, for purposes of
          determining any liability under the Securities Act of 1933, each
          filing of the Registrant's annual report pursuant to Section 13(a) or
          Section 15(d) of the Securities Exchange Act of 1934 (and, where
          applicable, each filing of an employee benefit plan's annual report
          pursuant to Section 15(d) of the Securities Exchange Act of 1934) that
          is incorporated by reference in the Registration Statement shall be
          deemed to be a new registration statement relating to the securities
          offered therein, and the offering of such securities at that time
          shall be deemed to be the initial bona fide offering thereof.

     (c)  Insofar as indemnification for liabilities arising under the
          Securities Act of 1933 may be permitted to directors, officers and
          controlling persons of the Registrant pursuant to the foregoing
          provisions, or otherwise, the Registrant has been advised that in the
          opinion of the Securities and Exchange Commission such indemnification
          is against public policy as expressed in the Securities Act of 1933
          and is, therefore, unenforceable.  In the event that a claim for
          indemnification against such liabilities (other than the payment by
          the Registrant of expenses incurred or paid by a director, officer or
          controlling person of the Registrant in the successful defense of any
          action, suit or proceeding) is asserted by such director, officer or
          controlling person in connection with the securities being registered,
          the Registrant will, unless in the opinion of its counsel the matter
          has been settled by controlling precedent, submit to a court of
          appropriate jurisdiction the question whether such indemnification by
          it is against public policy as expressed in the Act and will be
          governed by the final adjudication of such issue.


                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

<PAGE>

                                      -5-

SIGNATURES


     Pursuant to the requirements of the Securities Act of 1933, the Registrant,
ACT Manufacturing, Inc., certifies that it has reasonable grounds to believe
that it meets all of the requirements for filing on Form S-8 and has duly caused
this Registration Statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the Town of Hudson, Commonwealth of Massachusetts,
on this 8th day of August, 2001.

                              ACT MANUFACTURING, INC.


                              By:   /s/ John A. Pino
                                    ---------------------------
                                    John A. Pino
                                    President, Chief Executive Officer, and
                                    Chairman of the Board


                               POWER OF ATTORNEY

     We, the undersigned officers and directors of ACT Manufacturing, Inc.,
hereby severally constitute and appoint John A. Pino and Christopher L. Gorgone,
and each of them singly, our true and lawful attorneys, with full power to them
and each of them singly, to sign for us in our names in the capacities indicated
below, any amendments to this Registration Statement on Form S-8 (including
post-effective amendments), and to file the same, with all exhibits thereto and
other documents in connection therewith, with the Securities and Exchange
Commission, and generally to do all things in our names and on our behalf in our
capacities as officers and directors to enable ACT Manufacturing, Inc. to comply
with the provisions of the Securities Act of 1933, as amended, hereby ratifying
and confirming our signatures as they may be signed by our said attorneys, or
any of them, to said Registration Statement and all amendments thereto.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated.

<TABLE>
<CAPTION>
SIGNATURE                                              TITLE(S)                             DATE
---------                                              --------                             ----
<S>                                                   <C>                                   <C>
/s/ John A. Pino                                       President, Chief Executive           August 10, 2001
-----------------------------------------              Officer, and Chairman of the
John A. Pino                                           Board (Principal Executive
                                                       Officer)

</TABLE>

<PAGE>

                                      -6-

<TABLE>
<CAPTION>
SIGNATURE                                              TITLE(S)                             DATE
---------                                              --------                             ----
<S>                                                   <C>                                   <C>
/s/ Christopher L. Gorgone                             Interim Chief Financial              August 10, 2001
-----------------------------------------              Officer, Vice President of
Christopher L. Gorgone                                 Administration, Treasurer and
                                                       Clerk (Principal Financial and
                                                       Accounting Officer)

/s/ Bruce R. Gardner                                   Director                             August 10, 2001
-----------------------------------------
Bruce R. Gardner

/s/ Donald G. Polich                                   Director                             August 10, 2001
-----------------------------------------
Donald G. Polich

/s/ Edward T. Cuddy                                    Director                             August 10, 2001
-----------------------------------------
Edward T. Cuddy

/s/ Frederick W. Gibbs                                 Director                             August 10, 2001
-----------------------------------------
Frederick W. Gibbs
</TABLE>

<PAGE>

                                 Exhibit Index
                                 -------------

Item 8.  Exhibits.
         --------
<TABLE>
<CAPTION>
Exhibit No.                                  Description of Exhibit                        Page Number
------------------------  ------------------------------------------------------------  -----------------
<S>                       <C>                                                           <C>
Exhibit 4.1               Second Restated Articles of Organization of the Registrant
                          (filed as Exhibit 3.1 to the Registrant's Annual Report on
                          Form 10-K for the year ended December 31, 1995, and
                          incorporated herein by reference).

Exhibit 4.2               Articles of Amendment to the Second Restated Articles of
                          Organization of the Registrant (filed as Exhibit 4.2 to the
                          Registrant's Registration Statement on Form S-8, File No.
                          333-84231, and incorporated herein by reference).

Exhibit 4.3               Amended and Restated By-Laws of the Registrant, as amended
                          (filed as Exhibit 3.2 to the Registrant's Registration
                          Statement on Form S-1, File No. 33-89532, and incorporated
                          herein by reference).

Exhibit 4.4               Specimen certificate representing the Common Stock of the
                          Registrant (filed as Exhibit 4.1 to the Registrant's
                          Registration Statement on Form S-1, File No. 33-89532, and
                          incorporated herein by reference).

Exhibit 4.5*              Second Amended and Restated 1995 Stock Plan.

Exhibit 5.1*              Opinion of Testa, Hurwitz & Thibeault, LLP.

Exhibit 23.1              Consent of Testa, Hurwitz & Thibeault, LLP (contained in
                          Exhibit 5.1).

Exhibit 23.2*             Consent of Deloitte & Touche LLP.

Exhibit 24.1              Power of Attorney (included as part of the signature page
                          to this Registration Statement).
</TABLE>

*  Filed herewith.

