The mission of the Marin Community Foundation is to encourage and apply philanthropic contributions to help improve the human condition, embrace diversity, promote a humane and democratic society, and enhance the community's quality of life, now and for future generations. MCF was established in 1987 with the assets of a trust created by Leonard and Beryl H. Buck, long-time Marin residents with a desire to leave a legacy for people living in the County. Since then, over 400 individuals, families, businesses, community groups, and others have established funds at the Foundation. Grants made from these funds support a wide range of issues, both within the County and beyond. Besides making grants, MCF addresses community needs through many other efforts. These include convening groups and individuals to work on common problems and providing expertise to local nonprofit agencies to help them operate more effectively. MCF makes loans to local nonprofits and provides meeting space for local agencies. MCF also offers educational opportunities for the general public on current social issues. The Foundation is governed by a nine-member board of trustees and its President and CEO. MCF is one of the largest community foundations in the U.S., with assets of approximately $1 billion.

The Foundation makes an impact in two ways: Under its Strategic Plan, it makes discretionary grants to address critical issues in Marin County, CA. These include a focus on the development of affordable housing, closing the educational achievement gap, and ending the cycle of poverty.   Additionally, grants made from donor-advised and other funds established by individuals, families, and nonprofit groups address community issues in Marin, elsewhere in the U.S., and around the world.