AMENDMENT NUMBER 10 TO
                        PRINCIPAL UNDERWRITING AGREEMENT

      Pursuant to the Principal Underwriting Agreement between HARTFORD
SECURITIES DISTRIBUTION COMPANY, INC. and THE HARTFORD MUTUAL FUNDS, INC.
(formerly known as ITT Hartford Mutual Funds, Inc.) dated July 22, 1996, as
amended and as assigned to Hartford Investment Financial Services, LLC (formerly
known as Hartford Investment Financial Services Company) on November 1, 1998
(the "Agreement"), THE HARTFORD SELECT MIDCAP GROWTH FUND is hereby included as
a new Fund. All provisions in the Agreement shall apply to The Hartford Select
MidCap Growth Fund.

                                IN WITNESS WHEREOF, the parties hereto have
                                caused this amendment to be executed on the 31st
                                day of December, 2004.

                                          HARTFORD INVESTMENT
                                          FINANCIAL  SERVICES, LLC

                                          By: /s/ John C. Walters
                                              -------------------
                                          John C. Walters
                                          Executive Vice President

                                          THE HARTFORD MUTUAL FUNDS,
                                          INC.
                                          on behalf of: The Hartford Select
                                          MidCap Growth Fund

                                          By: /s/ David M. Znamierowski
                                              -------------------------
                                          David M. Znamierowski
                                          President