The Civil Marriage Collaborative (CMC) represents a unique collaboration among funders focused on LGBT (lesbian, gay, bisexual and transgender) issues and other progressive funders to strengthen a broad and diverse grassroots constituency to achieve civil marriage equality for same-sex couples in the United States. Recognizing that much of this important civil rights debate is unfolding state-by-state, CMC supports strategic efforts in states with concrete plans to win marriage equality in the context of the national marriage agenda. CMC has a particular interest in programs that have the ability to advance the public debate and include a strategy to engage and educate new public and community leaders. In addition, CMC encourages significant partnerships between LGBT and allied groups, with special emphasis on faith-based and people-of-color organizations.

Established in 2004, the Civil Marriage Collaborative is a funding collaborative initiated by Columbia Foundation, David Bohnett Foundation, Evelyn and Walter Haas, Jr. Fund, Gill Foundation, Open Society Institute, Overbrook Foundation, and an anonymous donor. The CMC is advised by five non-funder leaders who bring extensive knowledge of state-based LGBT organizations and the national movement to establish marriage equality. The CMC's leadership serves the additional important function of helping to educate the broader progressive philanthropic community.

In 2006 the CMC refined its grantmaking guidelines and now focuses its resources on efforts in states where same-sex marriage is most likely to be established in one to three years. The new strategy requires prospective grantees to demonstrate the probability of achieving marriage equality in their states with comprehensive plans that include measurable goals and timelines, even if they are applying for support for a specific campaign or project.