More than 15,000 men and women gathered yesterday for the city's 13th annual Gay and Lesbian Pride Day, a sun-filled festival of parading, picnicking and politicking for Washington's active homosexual community.

"It's beautiful," said Robert Belanger, a parade organizer, as he led the two-mile procession through Adams Morgan and Dupont Circle. "No hostility. No problems. Last year, we had some heckling. But this year, just great."

What began years ago as a small block party on 20th Street NW has grown into a large annual gathering to celebrate gay life styles and commemorate the homosexual community's struggle for civil rights, Belanger said. "And it's growing every year."

Groups representing gay scientists, doctors, senior citizens, athletes, Jews, Catholics, interracial couples and more marched in the parade or set up booths at the festival grounds at the P Street beach and the Francis recreation area at 24th and N streets NW.

With clusters of pink and lavender balloons overhead, the parade was led by young men who took turns carrying a flaming torch that will be carried cross-country to the first annual Gay Olympic Games in San Francisco.

Behind the torch, the D.C.'s Different Drummers Gay and Lesbian Marching Band, in snappy red and white uniforms, set the beat for the march, followed by their visiting counterparts in purple and white, the New York Gay Community Band. The D.C. Gay Men's Chorus marched, singing "Give me some men who are stout-hearted men" and taking some liberties with the original 1928 Oscar Hammerstein lyrics.

Along the parade route on Columbia Road and Connecticut Avenue in Northwest, hundreds of people, many with balloons saying "Celebrate the Gay Experience," waited in front of apartment buildings to join the parade. Near Dupont Circle, several eateries featured special gay-pride brunches for those joining the festivities.

"We don't have anything like this in Lynchburg . . . believe me," remarked Gary Bird, 29, a recently laid-off security guard, "You know, we're Rev. Jerry Falwell's hometown and he doesn't like us." Bird is an organizer of the Blue Ridge Lambda Alliance (BRLA), which takes its name from the Greek letter that has become a symbol of the gay community.

Last year, Bird said, the small Lynchburg gay organization had T-shirts that said only BRLA. When asked, some members said they belonged to the Blue Ridge Liturgical Association, Bird said.

Mayor Marion Barry and his leading challenger, Patricia Roberts Harris, were among the politicians who worked the crowd, but were not allowed to give speeches because Gay Pride organizers feared that election-year speeches would dominate the afternoon.

"I think that was an unfortunate decision," said Barry as he sat drinking a beer aboard a rented trolley car labelled the "Gay and Lesbian Band-Wagon for Mayor Barry."

"I'm still going to get some votes here today, though," Barry said, noting that his long-time support of gay rights has won him endorsement of the Gertrude Stein Democratic Club--though cracks have been noted in the usually solid gay political coalition, and many wonder whether any candidate will draw the kind of overwhelming support Barry drew from gays in 1978.

In addition to music, food, and partying, the festival had its more serious political side. The National Gay Task Force collected petition signatures against the proposed federal "Family Protection Act" that would bar federal funds for any group that promotes homosexuality and would prevent the Legal Services Corporation from defending homosexual rights.

While some expressed their gay pride with buttons and T-shirts that ranged from "Faggot" and "Queer" to the more low-key, "I'm One Too," Ed Murphy, 58, of New York City wore a sash that declared him to be "An Original Stonewaller."

Murphy, a burly gray-haired man with a thick New York Irish accent, said he has worked in gay bars for 30 years and was among the gays beaten and arrested in 1969 at the Stonewall Inn in New York. That battle between police and gays at an after-hours club became a rallying point for gay rights.

"We used to get raided all the time. The cops would take our liquor and our money and there was nothing we could do," he said, "It doesn't happen any more . . . We've come a long way. A lot has happened in 15 years."