<PAGE>


   As filed with the Securities and Exchange Commission on July 23, 1999
                                                      Registration No. 333-80141
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549

                                  ----------

                            AMENDMENT NO. 2 TO
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     Under
                           THE SECURITIES ACT OF 1933

                                  ----------
                                 DSL.net, Inc.
             (Exact name of registrant as specified in its charter)

                                  ----------
        Delaware                      4813                   06-1510312
     (State or other      (Primary Standard Industrial    (I.R.S. Employer
      jurisdiction        Classification Code Number)  Identification Number)
   of incorporation or
      organization)

                                  ----------
                                 DSL.net, Inc.
                              545 Long Wharf Drive
                              New Haven, CT 06511
                                 (203) 772-1000
  (Address, including zip code, and telephone number, including area code, of
                   registrant's principal executive offices)

                                  ----------
              David Struwas, President and Chief Executive Officer
                                 DSL.net, Inc.
                              545 Long Wharf Drive
                              New Haven, CT 06511
                                 (203) 772-1000
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)

                                  ----------
                                   Copies to:

  Mark H. Burnett, Esq.      Stephen Zamansky, Esq.   Ellen B. Corenswet, Esq.
    Testa, Hurwitz &             DSL.net, Inc.          Babak Yaghmaie, Esq.
     Thibeault, LLP           545 Long Wharf Drive       Brobeck, Phleger &
     125 High Street      New Haven, Connecticut 06511      Harrison LLP
  Boston, Massachusetts          (203) 772-1000          1633 Broadway, 47th
          02110                                                 Floor
     (617) 248-7000                                   New York, New York 10019
                                                           (212) 581-1600

                                  ----------
   Approximate date of commencement of proposed sale to the public: As soon as
practicable after this registration statement becomes effective.

                                  ----------

   If any of the securities being registered on this form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, check the following box. [_]

   If this form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, check the following box and
list the Securities Act registration statement number of the earlier effective
registration statement for the same offering. [_]

   If this form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [_]

   If this form is a post-effective amendment filed pursuant to Rule 462(d)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [_]

   If delivery of the prospectus is expected to be made pursuant to Rule 434,
check the following box. [X]

                                  ----------


   The registrant hereby amends this registration statement on such date or
dates as may be necessary to delay its effective date until the registrant
shall file a further amendment which specifically states that this registration
statement shall thereafter become effective in accordance with Section 8(a) of
the Securities Act of 1933 or until the registration statement shall become
effective on such date as the Securities and Exchange Commission, acting
pursuant to said Section 8(a), may determine.

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
<PAGE>


                             EXPLANATORY NOTE

   This Amendment No. 2 has been filed for the sole purpose of filing
additional exhibits to the Registration Statement.
<PAGE>

                                    PART II

                   INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 13. Other Expenses of Issuance and Distribution.

   Estimated expenses (other than underwriting discounts and commissions)
payable in connection with the sale of the common stock offered hereby are as
follows:

<TABLE>
      <S>                                                            <C>
      SEC registration fee.......................................... $   36,602
      NASD filing fee...............................................     12,000
      Nasdaq National Market listing fee............................     95,000
      Printing and engraving expenses...............................    175,000
      Legal fees and expenses.......................................    350,000
      Accounting fees and expenses..................................    350,000
      Blue Sky fees and expenses (including legal fees).............      5,000
      Transfer agent and registrar fees and expenses................      5,000
      Miscellaneous.................................................     21,398
                                                                     ----------
        Total....................................................... $1,050,000
                                                                     ==========
</TABLE>
---------------------
*To be filed by Amendment.

   DSL.net will bear all expenses shown above.

Item 14. Indemnification of Directors and Officers.

   The Delaware General Corporation Law and the certificate of incorporation of
DSL.net that will become effective immediately following this offering and the
by-laws as amended prior to this offering will provide for indemnification of
our directors and officers for liabilities and expenses that they may incur in
such capacities. In general, directors and officers will be indemnified with
respect to actions taken in good faith in a manner reasonably believed to be
in, or not opposed to, the best interests of DSL.net and, with respect to any
criminal action or proceeding, actions that the indemnitee had no reasonable
cause to believe were unlawful. Reference is made to our Amended and Restated
Certificate of Incorporation and Amended and Restated By-Laws filed as Exhibits
3.02 and 3.04 hereto, respectively.

   The Underwriting Agreement provides that the Underwriters are obligated,
under certain circumstances, to indemnify directors, officers and controlling
persons of DSL.net against certain liabilities, including liabilities under the
Securities Act of 1933, as amended (the "Securities Act"). Reference is made to
the form of Underwriting Agreement filed as Exhibit 1.01 hereto.

   In addition, we have an existing directors and officers liability insurance
policy.

Item 15. Recent Sales of Unregistered Securities.

   In the three years preceding the filing of this registration statement, the
Company has issued the following securities that were not registered under the
Securities Act:


                                      II-1
<PAGE>

   (a) Issuances of Capital Stock, Notes and Warrants

   In March 1998, DSL.net issued and sold an aggregate of (i) 5,089,634 shares
of common stock for an aggregate of $500 and (ii) 20,000 shares of a prior
Series A preferred stock for an aggregate of $50,000.

   In August 1998, DSL.net issued a promissory note in the aggregate principal
amount of $100,000.

   In November 1998, DSL.net issued five convertible promissory notes in the
aggregate principal amount of $350,000, two warrants to purchase an aggregate
31,250 shares of Series A preferred stock at a price of $1.00 per share and
rights to warrants to purchase 56,250 shares of old Series A preferred stock at
a price of $1.00 per share.

   In December 1998, DSL.net issued and sold an aggregate of (i) 7,634,451
shares of common stock in exchange for 20,000 shares of a prior series A
preferred stock and (ii) 4,071,707 shares of common stock in exchange for
promissory notes in an aggregate principal amount of $7,637.

   In January 1999, DSL.net issued and sold 3,500,000 shares of Series A
preferred stock and warrants to purchase 3,500,000 shares of a prior series B
preferred stock for an aggregate of $3,500,000, a portion of which was paid by
the conversion of two convertible promissory notes in the aggregate principal
amount of $125,000. In addition, DSL.net issued three warrants to purchase
56,250 shares of Series A preferred stock at a price of $1.00 per share in
exchange for the rights to warrants to purchase 56,250 warrants of Series A
preferred stock. DSL.net also issued an aggregate of 225,000 shares of Series A
preferred stock in conversion of three convertible promissory notes in the
aggregate principal amount of $225,000. Each outstanding share of Series A
preferred stock is convertible into 2.666 shares of common stock. Finally,
DSL.net issued 8 shares of common stock for aggregate consideration of $0.02.

   In March 1999, DSL.net issued and sold an aggregate of 436,256 shares of
common stock for services valued at $29,455. Based on subsequent events,
DSL.net recognized compensation expense of $587,457 in connection with the
issuance of these shares. In addition, DSL.net issued one warrant to purchase
41,726 shares of Series A preferred stock at an exercise price of $2.40 per
share.

   In April 1999, DSL.net issued and sold an aggregate of 6,500,000 shares of
Series B preferred stock in exchange for 3,500,000 shares of Series A preferred
stock and the cancellation of warrants to purchase 3,500,000 shares of a prior
series B preferred stock. In addition, in April 1999, DSL.net issued and sold
an aggregate of 2,785,516 shares of Series C preferred stock for aggregate
consideration of $10,000,002. Each outstanding share of preferred stock is
convertible into 2.666 shares of common stock.

   In May 1999, DSL.net issued and sold an aggregate of 2,868,069 shares of
Series D preferred stock for aggregate consideration of $30,000,001, including
a secured promissory note in an aggregate principal amount of $5,999,429, which
note has since been paid in full. Each outstanding share of Series D preferred
stock is convertible into 2.666 shares of common stock.


                                      II-2
<PAGE>

   In June 1999, DSL.net issued an aggregate of 95,603 shares of Series D
preferred stock for aggregate consideration of $1,000,007, including a secured
promissory note in an aggregate principal amount of $999,912. In addition, in
July 1999, DSL.net issued an aggregate of 939,086 shares of Series E preferred
stock for aggregate consideration of $18,499,994. Each outstanding share of
Series E preferred stock is convertible into 2.666 shares of common stock.

   (b) Grants and Exercises of Stock Options

   As of July 21, 1999, DSL.net has granted options to purchase an aggregate of
5,042,739 shares of common stock under the 1999 Stock Plan at exercise prices
ranging from $.04 to $7.39 for an aggregate purchase price of approximately
$2,862,170. No shares of common stock have been issued in connection with the
exercise of options.

   No underwriters were involved in the foregoing sales of securities. Such
sales were made in reliance upon an exemption from the registration provisions
of the Securities Act set forth in Section 4(2) thereof relative to sales by an
issuer not involving any public offering or the rules and regulations
thereunder, or, in the case of certain options to purchase common stock and
employee stock grants, Rule 701 under the Securities Act. All of the foregoing
securities are deemed restricted securities for purposes of the Securities Act.

                                      II-3
<PAGE>

Item 16. Exhibits and Financial Statement Schedules.

   (a) Exhibits:

<TABLE>
<CAPTION>
 Exhibit
   No.                                   Exhibit
 -------                                 -------
 <C>      <S>
  1.01*   Form of Underwriting Agreement.

  3.01*   Restated Certificate of Incorporation of DSL.net, as amended.

  3.02*   Form of Amended and Restated Certificate of Incorporation of DSL.net
          (to be filed immediately after the closing of the offering).

  3.03*   By-Laws of DSL.net.

  3.04*   Amended and Restated By-laws of DSL.net (to be effective immediately
          after the closing of the offering).

  4.01*   Specimen Certificate for shares of DSL.net's Common Stock.

  4.02*   Description of Capital Stock (contained in the Certificate of
          Incorporation filed as Exhibit 3.02).

  4.03+   Form of Stock Purchase Warrant dated as of November 18, 1998 between
          DSL.net and certain investors.

  4.04+   Form of Warrant Agreement dated as of January  , 1999 between DSL.net
          and certain investors.

  4.05+   Stock Subscription Warrant dated as of March 4, 1999 by and between
          DSL.net and Comdisco, Inc.

  5.01*   Legal Opinion of Testa, Hurwitz & Thibeault, LLP.

 10.01**+ 1999 Stock Plan.

 10.02+   Registration Rights Provisions contained in the Amended and Restated
          Investors' Rights Agreement dated as of May 12, 1999 between DSL.net
          and the purchasers named therein.

 10.03*   Master Lease Agreement dated as of March 4, 1999 between Comdisco,
          Inc. and DSL.net, as modified by the Addendum thereto.

 10.04+   Credit Agreement dated as of May 12, 1999 by and between DSL.net and
          Fleet National Bank.

 10.05+   Security Agreement dated as of May 12, 1999 by and between DSL.net
          and Fleet National Bank.

 10.06+   Lease Agreement dated February 5, 1999 by and between DSL.net and
          Long Wharf Drive, LLC., as amended.

 10.07*   Amended and Restated Shareholders' Agreement, as amended, by and
          among DSL.net and certain investors.

 23.01*   Consent of Testa, Hurwitz & Thibeault, LLP (contained in Exhibit
          5.01).

 23.02+   Consent of PricewaterhouseCoopers, LLP.

 24.01    Power of Attorney (contained on page II-6).

 27.01    Financial Data Schedule.
</TABLE>
---------------------
*  To be filed by amendment.
** Indicates a management contract or any compensatory plan, contract or
   arrangement.
+  Previously filed.

   (b) Financial Statement Schedules

   None.

   All other schedules for which provision is made in the applicable accounting
regulations of the Securities and Exchange Commission are not required under
the related instructions or are inapplicable, and therefore have been omitted.

                                      II-4
<PAGE>

Item 17. Undertakings.

   Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
registrant pursuant to the provisions described in Item 14 above, 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 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
Securities Act and will be governed by the final adjudication of such issue.

   The undersigned registrant hereby undertakes (1) to provide to the
underwriters at the closing specified in the underwriting agreement,
certificates in such denominations and registered in such names as required by
the underwriters to permit prompt delivery to each purchaser; (2) that for
purposes of determining any liability under the Securities Act, the information
omitted from the form of prospectus filed as part of this registration
statement in reliance upon Rule 430A and contained in a form of prospectus
filed by the registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the
Securities Act shall be deemed to be part of this registration statement as of
the time it was declared effective; and (3) that for the purpose of determining
any liability under the Securities Act, each post-effective amendment that
contains a form of prospectus 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.

                                      II-5
<PAGE>
                                   SIGNATURES

   Pursuant to the requirements of the Securities Act of 1933, as amended, the
registrant has duly caused this Amendment No. 2 to the Registration Statement
(File No. 333-80141) to be signed on its behalf by the undersigned, thereunto
duly authorized, in New Haven, Connecticut on July 23, 1999.

                                          DSL.NET, INC.

                                          By: /s/ Stephen Zamansky
                                          ---------------------------------

                                             Stephen Zamansky

                                             Vice President  and General
                                             Counsel

                                   SIGNATURES

   Pursuant to the requirements of the Securities Act of 1933, this Amendment
No. 2 to the 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>
                  *                    President, Chief Executive    July 23, 1999
______________________________________  Officer and Director
           David F. Struwas             (Principal Executive
                                        Officer)

                  *                    Chief Financial Officer       July 23, 1999
______________________________________  and Vice President,
           Robert Q. Berlin             Strategic Planning
                                        (Principal Financial and
                                        Accounting Officer)

                  *                    Director                      July 23, 1999
______________________________________
          Robert Gilbertson

                  *                    Director                      July 23, 1999
______________________________________
         William J. Marshall

                  *                    Director                      July 23, 1999
______________________________________
           William Seifert

                  *                    Director                      July 23, 1999
______________________________________
           James D. Marver

                  *                    Director                      July 23, 1999
______________________________________
</TABLE>     Paul K. Sun

   /s/ Stephen Zamansky
*By: ___________________________

   Stephen Zamansky
   as Attorney-in-Fact

                                      II-6
<PAGE>

                                 Exhibit Index

<TABLE>
<CAPTION>
 Exhibit
   No.                                   Exhibit
 -------                                 -------
 <C>      <S>
  1.01*   Form of Underwriting Agreement.

  3.01*   Restated Certificate of Incorporation of DSL.net, as amended.

  3.02*   Form of Amended and Restated Certificate of Incorporation of DSL.net
          (to be filed immediately after the closing of the offering).

  3.03*   By-Laws of DSL.net.

  3.04*   Amended and Restated By-laws of DSL.net (to be effective immediately
          after the closing of the offering).

  4.01*   Specimen Certificate for shares of DSL.net's Common Stock.

  4.02*   Description of Capital Stock (contained in the Certificate of
          Incorporation filed as Exhibit 3.02).

  4.03+   Form of Stock Purchase Warrant dated as of November 18, 1998 between
          DSL.net and certain investors.

  4.04+   Form of Warrant Agreement dated as of January 8, 1999 between DSL.net
          and certain investors.

  4.05+   Stock Subscription Warrant dated as of March 4, 1999 by and between
          DSL.net and Comdisco, Inc.

  5.01*   Legal Opinion of Testa, Hurwitz & Thibeault, LLP.

 10.01**+ 1999 Stock Plan.

 10.02+   Registration Rights Provisions contained in the Amended and Restated
          Investors' Rights Agreement dated as of May 12, 1999 between DSL.net
          and the purchasers named therein.

 10.03*   Master Lease Agreement dated as of March 4, 1999 between Comdisco,
          Inc. and DSL.net, as modified by the Addendum thereto.

 10.04+   Credit Agreement dated as of May 12, 1999 by and between DSL.net and
          Fleet National Bank.

 10.05+   Security Agreement dated as of May 12, 1999 by and between DSL.net
          and Fleet National Bank.

 10.06+   Lease Agreement dated February 5, 1999 by and between DSL.net and
          Long Wharf Drive, LLC., as amended.

 10.07*   Amended and Restated Shareholders' Agreement, as amended, by and
          among DSL.net and certain investors, as amended.

 23.01*   Consent of Testa, Hurwitz & Thibeault, LLP (contained in Exhibit
          5.01).

 23.02+   Consent of PricewaterhouseCoopers, LLP.

 24.01    Power of Attorney (contained on page II-6).
 27.01    Financial Data Schedule.
</TABLE>
---------------------
*  To be filed by amendment.
** Indicates a management contract or any compensatory plan, contract or
   arrangement.
+  Previously filed.