In a way, this year marks an anniversary within Washington's gay community. Twenty years ago, in November 1957, a young government astronomer here named Franklin Kameny was ordered to appear for questioning before a panel of personnel.

The investigators said: "Dr. Kameny, we have information which leads us to believe that you are a homosexual.

"What's your information?" said Kameny. The investigators declined to answer.

"True or untrue," said Kameny, "I don't think it's any of your business. "He was fired from his job.

"I took that," Kameny recalled not long ago, "as a declaration of war upon me by my government." He appealed his firing; the appeal was rejected. He sought support from other homosexuals and found instead a hushed, isolated community, terrified by the McCarthy era into lives of furtive bar-prowling.

Kameny turned elsewhere: to New York, to Los Angeles, to the few cities harboring the beginnings of gay rights movements.He learned then of the Mattachine Society, a national group whose mysterious name was in itself an indication of the movement's timidity. Mattachines had been court jesters of the Middle Ages, the costumed entertainers whose masks allowed them to offer otherwise forbidden social commentary.

Truth from behind the mask, Kameny wanted to bring the society to Washington. Mattachine of New York sent preliminary meeting notices to local names on its mailing list, and one evening in the fall of 1961, 13 men met in a downtown hotel room to plan the fouding of the Washington Mattachine.

It was a tentative, closed-door meeting, with no outside publicity and few real names used. Early on, as Kameny recalls it, someone recognized one of the participants. He was a District of Columbia police vice squad officer, his gun bulging discreetly under his jacket, and he knew of the meeting according to Kameny, because the police department - using a pseudonym - was on the Mattachine Society's mailing list.

In the uneasy atmosphere, Washington's first homosexual organization was born. Mattachine's membership grew slowly over the years, with sporadic gay rights demonstrations at the White House, the Pentagon, the State Department.

Then in June 1969, a police sweep of Greenwich Village homosexuals erupted into a street battle that changed the whole nature of the movement. Gays today call it the Stonewall Rebellion, after the bar where fighting broke out, and they speak of Stonewall like antiwar activists remembering Kent State, or townspeople recalling the great flood - the crisis that reshaped lives.

Movements need rallying cries, and now homosexuals had one. Stonewall hurled a generation of young homosexuals into radical politics, spawning the Gay Liberation. Front and then the Gay Activists Alliance. In parades and demonstrations, gays lunged for the first time into flamboyant displays of their homosexuality - Gay is Good, Be Gay and Be Proud. It hit Washington not long after New York.

The demonstrations are less frequent now, and overshadowed by quieter work: Gay activists Alliance political lobbying, an April conference on women and the lesbian community, plans for a publicity campaign of Metrobus advertisements that will read, "Someone in your life is gay."

Still, there are rallies, like the one organized yesterday to protest the Supreme Court's year-old ruling upholding states' rights to outlaw sodomy. Another is planned today at Lafayette Park to protest Anita Bryant's work in Florida. And June 12 is Gay Pride Day, which in the aftermath of the Dade County election will be either a celebration or a wake.