The first ordained minister of a major religious sect in the U.S. or Canada to come out as gay was the UU Minister James Stoll in 1969. There have been UUA resolutions supporting people regardless of sexual orientation since 1970. Unitarian Universalism was the first denomination to accept openly transgender people as full members with eligibility to become clergy; in 1988 the first openly transgender person was ordained by the Unitarian Universalist Association. The UUA has had a popular program for a church wanting to become a "Welcoming Congregation" for LGBT people since 1989. UUA has officially supported UUA clergy performing Services of Union between same-sex couples since 1984, and has supported same-sex marriage since 1996. In 2002, Sean Dennison became the first openly transgender person in the Unitarian Universalist ministry called to serve a congregation; he was called to South Valley UU Society, Salt Lake City, UT. In 2004 UU Minister Rev. Debra Haffner of The Religious Institute on Sexual Morality, Justice, and Healing published An Open Letter on Religious Leaders on Marriage Equality to affirm same-sex marriage from a multi-faith perspective.
The UUA maintains an office called Lesbian, Gay, Bisexual, Transgender, and Queer Ministries (LGBTQ Ministries) (which operates the Welcoming Congregation program). Established in 1973 as the "Office of Gay Affairs", it was the first major national religious sect to open a dedicated office for LGBT inclusion. There is also a fellowship of LGBT Unitarian Universalists and supporters called Interweave Continental. Interweave is a related organization of the UUA. Any UU church desiring to become a Welcoming Congregation must meet the requirements set out in The Welcoming Congregation Handbook by LGBTQ Ministries. Once the requirements have been met, the UUA designates that church as a Welcoming Congregation and adds an icon to the listing in the UUA Directory. Usually, the Welcoming Committee evolves into an Interweave Chapter. Each chapter requests financial and advocacy support from the fellowship with which it is connected.
The Canadian Unitarian Council (CUC) similarly operates a Gender and Sexual Diversity Monitoring Group, and like the UUA (of which it became autonomous in 2002), has Welcoming Congregations. The Canadian Unitarian Universalist congregations perform same-sex marriages and the CUC supports this work through its Lay Chaplaincy program. The first same-sex marriage performed by a church in Canada (after 1972 a civil same-sex marriage for Michel Girouard and Rejean Tremblay of Montreal) was that of Chris Vogel and Richard North, married by the First Unitarian Universalist Church of Winnipeg on February 11, 1974 officiated by Unitarian Minister Rev. Norm Naylor. The Unitarian Universalist Church was responsible for the first same-sex marriages performed in Manitoba, Ontario, Alberta, British Columbia, Nova Scotia, and Saskatchewan, mostly in the 1970s, although the provincial governments often refused to recognize the marriages at the time.