Exhibit 10.1

December 29, 2006

Brian Roberts

c/o Digitas Inc.

33 Arch Street

Boston, MA 02110

Dear Brian,

This letter confirms our recent discussions concerning the terms of the Change
of Control provisions of your Digitas Inc. Employment Agreement and your
continued role with Digitas Inc. following the acquisition of Digitas Inc. by
Publicis Groupe S.A. (“Publicis”) pursuant to the Agreement and Plan of Merger,
dated December 20, 2006, by and among Digitas Inc., Publicis and Pacific
Acquisition Corp., an indirect wholly-owned subsidiary of Publicis (the “Merger
Agreement”).

We confirm that your Digitas Inc. Employment Agreement dated June 22, 2001, as
amended (the “Employment Agreement”) remains in force and effect, subject to the
agreements set forth in this paragraph, which constitute a valid amendment of
such agreement. We hereby agree that the Acceptance Date (as defined in the
Merger Agreement) will constitute a Change of Control for purposes of such
agreement and that you will be treated under such agreement as if you had
incurred a termination for Good Reason (within the meaning of Section 6(d) of
the Employment Agreement) as of the Acceptance Date (with the Notice and Cure
provisions of the Employment Agreement waived) and it is acknowledged and agreed
that you shall be entitled to and paid the benefits specified in Sections 6(e)
and 6(f) of the Employment Agreement as if the Acceptance Date were the Date of
Termination (as defined in the Employment Agreement), except that (x) subject to
the limitation set forth in the next sentence, the salary continuation will be
paid in installments for the first six months following the Acceptance Date but
the remaining installments will be paid in a lump sum as soon as practicable
following the six-month anniversary of the Acceptance Date and (y) any insurance
continuation shall begin on the day following your actual termination of
employment. In the event that you voluntarily terminate employment or your
employment is terminated for cause (as defined below) prior to the end of the
Transition Period (as defined below), the remaining salary continuation will not
be paid in a lump sum following the six-month anniversary and will instead
continue to be paid in installments through the second anniversary of the
Acceptance Date. The payments and benefits being made pursuant to this paragraph
are in lieu of any future termination-based payments under your Employment
Agreement or otherwise (except as set forth below with respect to the Retention
Bonus), and you waive any right to severance (including under Sections 6(e) and
6(f) of the Employment Agreement) upon a future termination of employment from
Digitas Inc. and its affiliates.

As we have discussed, we would very much like for you to remain with the Company
for the six-month period following the Acceptance Date (the “Transition
Period”), with the understanding that at the end of that period, we will
determine whether or not there is a continued role for you at Digitas Inc. or
elsewhere in the Publicis organization. During the Transition Period you will
receive (i) a base salary at a rate no less than your base salary immediately
prior to the Closing Date, and (ii) such other benefits as are customarily
provided by Digitas to its similarly situated senior executives.

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December 29, 2006

Page 2

In addition, upon the earlier of the expiration of the Transition Period
(assuming you have remained continuously employed through the conclusion of such
period) or the earlier date of termination without cause (as defined below) of
your employment by Digitas Inc. or Publicis, you shall be paid a lump sum
retention bonus of $200,000 (the “Retention Bonus”). In the event that, prior to
the expiration of the Transition Period, your employment is terminated for cause
or you voluntarily terminate employment, you will forfeit all rights to the
Retention Bonus. For purposes of this Agreement, “cause” shall be defined as the
willful commission of misconduct having a material adverse impact on Digitas
Inc. or the substantial and continuing failure to perform your assigned duties
despite having received reasonable notice of such deficiency and an appropriate
period to cure.

If any of the compensation payable under this Agreement is considered
nonqualified deferred compensation within the meaning of Internal Revenue Code
Section 409A, and if payment of such compensation would violate Section 409A
then, notwithstanding the other provisions of this Agreement, such compensation
will be paid at the earliest time that will not violate such Section 409A.

By signing below, you and Digitas Inc. agree to be bound by the terms stated
herein. It is understood that, in the event the Merger Agreement is terminated
prior to an Acceptance Date, this Agreement shall become null and void and of no
effect.

We look forward to continuing to work together in the future.

 

Sincerely,

/s/ David W. Kenny

David W. Kenny, Chief Executive Officer

Digitas Inc.

 

Acknowledged and Agreed:

/s/ Brian Roberts

Brian Roberts