UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C.

                                   Form 13F

                              Form 13F COVER PAGE

Report for the Calendar Year or Quarter Ended: March 31, 2011

Check here if Amendment [_]; Amendment Number: __________
   This Amendment (Check only one.):     [_] is a restatement.
                                         [_] adds new holdings entries.

Institutional Investment Manager Filing this Report:

Name:        Bain Capital IX Coinvestment Fund, L.P.*
Address:     111 Huntington Avenue
             Boston, MA 02199

Form 13F File Number: 28-13941

The institutional investment manager filing this report and the person by whom
it is signed hereby represent that the person signing the report is authorized
to submit it, that all information contained herein is true, correct and
complete, and that it is understood that all required items, statements,
schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:

Name:        Michael F. Goss
Title:       Managing Director and Chief Operating Officer of Bain
             Capital Investors, LLC, which is the general partner
             of Bain Capital Partners IX, L.P., which is the general
             partner of Bain Capital IX Coinvestment Fund, L.P.
Phone:       (617) 516-2000

Signature, Place, and Date of Signing:

        /s/ Michael F. Goss             Boston, MA          5/16/11
      ------------------------         -------------        -------
            [Signature]                [City, State]         [Date]

* The report on Form 13F for the period ended March 31, 2011 for Bain Capital
  IX Coinvestment Fund, L.P. (the "Fund") is being filed by Bain Capital
  Investors, LLC, the general partner of Bain Capital Partners IX, L.P., which
  is the general partner of the Fund.

Report Type (Check only one.):

[_] 13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager
    are reported in this report.)

[X] 13F NOTICE. (Check here if no holdings reported are in this report, and all
    holdings are reported by other reporting manager(s).)

[_] 13F COMBINATION REPORT. (Check here if a portion of the holdings for this
    reporting manager are reported in this report and a portion are reported by
    other reporting manager(s).)



List of Other Managers Reporting for this Manager:

     Form 13F File Number           Name
     --------------------           ----------------------------------
     28-11185                       Bain Capital Investors, LLC
     28-13942                       Bain Capital Partners IX, L.P.