In 1974, SETA was founded in Helsinki as a response to the increasing need for a structured organisation to advocate for LGBT rights in Finland. The founders were motivated by the desire to combat pervasive discrimination and societal stigma faced by sexual minorities. At a time when homosexuality was classified as a mental disorder by the World Health Organization, the need for advocacy and community support was critical. SETA's establishment marked the beginning of a formal movement for the recognition and equal rights of LGBT individuals in Finland.

The organisation quickly took on various roles, including legal advocacy, public awareness campaigns, and providing resources for LGBT individuals. One notable initiative was their push for the decriminalization of homosexuality, which contributed to changing public perceptions and legislative progress. SETA faced significant challenges, including societal bias and limited media representation, but used grassroots activism and public engagement to raise awareness and foster community.

Over the years, SETA grew to become a national network, uniting various regional groups to strengthen the collective voice for LGBT rights. They worked on projects addressing issues like discrimination in workplaces, mental health resources, and educational outreach. This collaboration proved instrumental in influencing legislative changes in Finland, including the introduction of anti-discrimination laws and the eventual legalization of same-sex marriage in 2017.