- Civil marriage equality in effect at the state level since 2012. (Same-sex couples may legally marry.)
- The Puyallup Tribe of Indians legalized marriage equality 9 July 2014.
- Marriage equality recognized by the Confederated Tribes of the Colville Reservation since 5 September 2013.
- The Suquamish Tribe legalized marriage equality on 1 August 2011.
- Washington is home of the 1974 legal case Singer v. Hara, in which the court ruled against the plaintiffs, a gay male couple, John Singer and Paul Barwick. The plaintiffs had argued that Washington marriage statutes did not prohibit same-gender marriages and therefore a license should be issued to them.