Harry Hay, 90, a founder of the gay movement and a member of the Communist Party, which banned homosexuals, died of lung cancer Oct. 24 at his home in San Francisco.

From the 1950s on, in frequent lectures and essays, he chronicled his transition from a married man with two children in the 1940s to a gay activist who founded the Mattachine Society, a national support group for gays, in the early 1950s. He left the Communist Party in 1951 and was expelled from the Mattachines several years later for his extreme politics. He then went on to help launch the Radical Faeries, a gay spirituality movement that started in 1979.

Mr. Hay spent most of his life advocating a coalition of all minorities and arguing that each group's cause was part of a larger progressive movement. In the 1970s, he supported equal rights for women, as well as American Indian issues. In the 1980s, he helped found the gay caucus of Jesse L. Jackson's Rainbow Coalition.

His dual identity as a Communist and a gay activist set Mr. Hay apart among leaders of the gay movement. His separate-but-equal stance forced an early debate within the movement that still continues. Should gay men and lesbians assimilate into mainstream society or not? Mr. Hay was against assimilation and emphasized his position by his gender-bender style of dress. He wore the knit cap of a macho longshoreman, a pigtail and a strand of pearls.

Mr. Hay was born in Worthing, England, the son of a mining engineer. From age 11, he knew that he was attracted to boys, not girls. In those years, he later explained, the term "homosexual" was not included in most dictionaries. "We had no words to describe ourselves," he said. He referred to homosexuals as "temperamental guys."

His father moved the family to Los Angeles in 1919, and Hay entered Stanford University in 1930. But he soon dropped out and returned to Los Angeles to pursue his interest in acting. He met Will Geer, an actor and political leftist best remembered as Grandpa on the 1970s television series "The Waltons."

Geer introduced Mr. Hay to the city's Communist Party, and by 1935 both men were members. Soon after, Mr. Hay stumbled on his life's work when he joined a maritime strike in San Francisco that turned violent. The National Guard was called in, two people were killed, many others were injured and Hay's passion for political activism and community organizing was ignited.

Mr. Hay married Anita Platky, an activist in the party. They stayed together for 13 years and adopted two daughters, Hannah and Kate. But marriage didn't change him. "I knew I was gay in every bone of my body," he later said. The couple divorced in 1951 on the grounds of extreme cruelty. His family was deeply wounded by Hay's politics and his ongoing gay affairs.

Also that year he quit the Communist Party. By then, Soviet dictator Josef Stalin was shipping homosexuals to Siberia as social deviants.

In 1950, Mr. Hay met Rudi Gernreich, a fledgling fashion designer, at a dance studio in Los Angeles. Gernreich was destined for fame as the designer of the topless bathing suit for women in the mid-1960s. The two men shared political ideals, and Gernreich encouraged Mr. Hay to start the Mattachine Society, which he had first envisioned in the late 1940s. Hay took the name from a secret all-male society of 15th-century Europe and structured the group after the Communist Party's cells.

When the Mattachines met for discussions, members brought a "cover" girl, a female friend or relative. It was against the law in California for gay men to meet in groups.

In 1955, Mr. Hay was called before the House Un-American Activities Committee, and although he was not charged with any crime, he dropped out of the limelight after that. In 1963, he met John Burnside, the inventor of the teleidoscope, a variation on the kaleidoscope, who became his companion. They moved to New Mexico in 1970 and managed a trading post on a Pueblo Indian reservation north of Santa Fe.

Survivors include his companion and two daughters.

Harry Hay, left, with partner John Burnside at their home in San Francisco

in July. His dual identity as a Communist and a gay activist set him apart.