The Civil Marriage Collaborative was launched through the efforts of the Open Society Foundations and six funding partners in 2004. The CMC supports state organizations working to advance the legal recognition of same-sex relationships. CMC funds enable these historically under-funded organizations to build capacity and be more effective advocates in state-based efforts to secure marriage equality. CMC also encourages partnerships between LGBTQ and allied groups, with a special emphasis on faith-based and people of color led organizations.
CMC is housed at the Proteus Fund, a publicly support 501(c)3 organization that manages donor advised funds and serves as a vehicle to educate donors and increase philanthropy.