The International Day Against Homophobia, Transphobia and Biphobia is not one centralised campaign; rather it is a moment that everyone can take advantage of to take action.

The date of May 17th was specifically chosen to commemorate the World Health Organization’s decision in 1990 to declassify homosexuality as a mental disorder.

The International Day against Homophobia, Transphobia and Biphobia has received official recognition from several States, international institutions as the European Parliament, and by countless local authorities. Most United Nations agencies also mark the Day with specific events

http://dayagainsthomophobia.org