The Mattachine society was one of the first American gay rights groups and became the first well-known modern LGBT group in the world.
HI I'm Harry Hay, and I actually developed my skills of large group organization through my time in a Marxist group.
Harry Hay is regarded by many as the founding father of the modern day LGBT movement. He was one of the founders of the Mattachine Society and assisted with the structure of the society, which he developed to be similar in structure to the communist party.
There were many laws in place at the time that discriminated against members of the LGBT community. Ranging from no public displays of same sex relationships justified by "public lewdness and indecency", to something as ridiculous as requiring each gender to wear no more than one clothing article f the opposite gender, and at least 3 articles of clothing of their own gender. These laws were often vague and easily interpreted to specifically discriminate against those seen to be homosexuals.
Sorry bud, but I'm seeing one too many articles of clothing that I consider to be of the opposite gender. Police brutality time.
A lot of the time the members would wear normal clothing to show that homosexuals could be members of society like anybody else, and to not be charged with the periods ridiculous gender clothing laws.