Lesbian, gay, bisexual, and transgender (LGBT) rights in the U.S. state of Washington have evolved significantly since the late 20th century. Same-sex sexual activity was legalized in 1976. LGBT people are fully protected from discrimination in the areas of employment, housing and public accommodations; the state enacting comprehensive anti-discrimination legislation regarding sexual orientation and gender identity in 2006. Same-sex marriage has been legal since 2012, and same-sex couples are allowed to adopt. Conversion therapy on minors has also been illegal since 2018.
Washington is frequently referred to as one of the United States' most LGBT-friendly states, and its largest city Seattle has a thriving LGBT community, ranked as the fifth largest in the country. Opinion polling has shown that a majority of Washingtonians support same-sex marriage and LGBT rights. A 2019 survey from the Public Religion Research Institute showed that 74% of residents supported anti-discrimination laws protecting LGBT people. In November 2012, voters approved a same-sex marriage law in Referendum 74.