On July 4, 1965, with protest signs raised above their heads, 40 marchers outside Philadelphia's Independence Hall showed many people their first glimpse of lesbian, gay and bisexual Americans.
The protesters and their leaders, Frank Kameny and Barbara Gittings, were setting in motion the decision by the American Psychiatric Association (APA) to remove homosexuality as a mental illness less than a decade later.
The events of 50 years ago are the focus of the National LGBT 50th Anniversary Celebration being held this weekend throughout Philadelphia.
At the time, the protestors were the opposite of most people’s distorted ideas of what homosexuality was, said Caitlin Ryan, director of the Family Acceptance Project at San Francisco State University.
"Homosexuality was considered a mental illness, deviant and immoral," she said. "If it were not for the early work of the health and social systems to change that, I don’t think we would have made the advances that we’ve made since then."
The process to remove "homosexuality" from the APA's Diagnostic and Statistical Manual (DSM) of Mental Disorders began in earnest when activists, led by Kameny and Gittings, interrupted the organization's 1970 meeting in San Francisco.
"The gay activists were the catalyst," said New York City-based psychiatrist and psychoanalyst Dr. Jack Drescher.
The activists were offered their own panel at the APA's next meeting and then again in 1972, when Dr. John Fryer spoke alongside Kameny and Gittings.
Fryer, a psychiatrist, could have lost his license if it were known that he was gay. Using a voice-changing microphone and wearing a mask, he spoke about the plight of gay psychiatrists, who had to keep their sexual orientations secret.
"It was the beginning of the dialogue," said Drescher, who has chronicled the history of LGBT mental health and worked in several capacities within the APA. "We had these panels of people discussing the pros and cons of the issue. Then you had committee meetings."
Along with the APA's willingness to hear from the activists, there was a growing body of medical literature reporting that lesbian, gay and bisexual people were no more mentally ill than the general population.
For example, California psychologist Evelyn Hooker had experts compare psychological test results from 30 gay men and 30 straight men. The experts found no more evidence of mental illness in gay men than in straight men.
"At that time no one had studied normality in homosexuality and the early research on homosexuality came out of the prisons and mental health institutions," Ryan told Reuters Health.
After debate among the APA's scientific committees, the organization's board of trustees removed "homosexuality" from the DSM in 1973.
"I think it took a long time for people to fully appreciate what had happened," Drescher said.
He said without "homosexuality" in the DSM, people in various areas of society had trouble rationalizing discrimination.
Progress was slow, however. For example, until the late 1980s, homosexuals could be blocked from immigrating to the U.S.
Also, Drescher said, it was not until the early 1990s that the U.S. debated Don't Ask, Don't Tell, which allowed closeted lesbian, gay and bisexual people to serve in the military.
"Other than talking about HIV, that was the first major public policy to date when people talked about what does it mean to be gay," Drescher said.
Even in the mental health profession itself, Ryan noted, lesbian, gay and bisexual people would have difficulty finding jobs or getting into professional schools for many years.
Drescher said it took time for the profession to purge old dogma that being lesbian, gay or bisexual is a mental illness.
"Now nobody is trained that homosexuality is an illness," he said.
The work of early activists paved the way for current accomplishments in LGBT rights and health, Ryan said.
"We’ve had 60 years of research on sexual orientation," Ryan said. "It helped create an empirical foundation for these policy changes."