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                                                                   Exhibit 10.18

                       ADDITIONAL COMPENSATION AGREEMENT


     AGREEMENT made this 29th day of December, 1998 between dsl.net, inc., a
Delaware corporation (the "Company"), and David Struwas, President and Chief
Executive Officer of the Company (the "Executive").

                             W I T N E S S E T H:

     WHEREAS, the Executive is, and will be, rendering valuable assistance to
the Company; and

     WHEREAS, it is important to the Company to retain an experienced management
team, and the Company, in recognition of such services rendered and to be
rendered, wishes to award the Executive a retention bonus.

     NOW, THEREFORE, in consideration of the premises and the services rendered
and to be rendered by the Executive to the Company, the parties hereto agree as
follows:

     1. Compensation. The Company agrees to pay to the Executive as
compensation, in addition to all other compensation paid or payable to him by
the Company, (a) an amount such that the net amount paid to the Executive after
all required withholding pursuant to all applicable federal, state or other
taxes with respect to such payment, equals $6,681.82 plus interest thereon at a
rate of 5.56% from the date hereof to the date of such payment, and (b) any
additional amount that the Executive owes on account of federal, state or other
income taxes with respect to the amount paid to the Executive pursuant to (a)
above.

     2. Payment. The amount payable pursuant to Section 1(a) shall be paid to
the Executive as early as practicable in calendar year 1999. The Company may
either pay such amount in cash or forgive any indebtedness of Executive to the
Company, up to such amount, in lieu of cash payment thereof. The amount payable
pursuant to Section 1(b) shall be paid to the Executive within 30 days after the
Executive notifies the Company that such amount is due.

     3. Withholding. The Company shall be permitted to withhold from any payment
to the Executive hereunder all federal, state and other taxes which may be
required with respect to such payment.
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     4. Miscellaneous.

        (a) Binding Effect; Assignment. The provisions of this Agreement shall
be binding upon and shall inure to the benefit of the Company and its successors
and assigns and the Executive and his heirs and legal representatives.

        (b) Amendments. This Agreement may not be amended or modified except by
an instrument in writing signed by both parties hereto.

        (c) Law Governing. This Agreement shall be governed by and enforced in
accordance with the laws of the State of Connecticut, without regard to the
conflicts of laws provision thereof.

     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the date first above written.


                                             DSL.NET, INC.


                                             By:_____________________________
                                                Name:
                                                Title:


                                             ________________________________
                                             David Struwas