The Rainbow Project is the largest LGBT organisation (by number of staff members) on the island of Ireland and has two central offices, in Belfast and Foyle, Derry.

The organisation was established in 1994 by a group of volunteers who were concerned about the spread of HIV infection within the gay male population of Northern Ireland.

As a result of this research, the project began to offer information on HIV/AIDS and other sexually transmitted infections (STIs), distributing safer sex materials and leaflets at commercial gay venues and LGBT events.

Although initial work was focused on HIV and STI prevention, it became clear that service-users had additional support needs related to their physical health generally as well as their mental & emotional well-being.

In Partnership with Irish Congress of Trade Unions and Amnesty International,[1] The Rainbow Project organised a mass public rally in support of equal marriage on 13 June 2015, with a 20,000 person turnout.