A couple of years ago, a Latin music concert in Washington would probably have been attended exclusive by members of the Spanish-speaking community. As a matter of fact, when Tipica '73 played at the Shoreham Hotel's Regency Ballroom two summers ago in the area's first major "salsa" show, that's exactly what happened.

But mixed in with the Latin families and singles at yesterday afternoon's "Latin Music Fair" at Community West Park in Adams Morgan (the opening event of the week-long Festival Hispanoamericano) were what the festival's organizing committee refers to as the "Anglos and Afros": the young whites and black who traditionally have been most receptive to rock 'n' roll and soul music. They may not have understood they lyrics of what they were hearing, but that didn't keep them from dancing.

That's what Latin music is supposed to do, of course: They don't call it "salsa" for nothing. The music that takes its name from the salsa picante or "hot sauce" used in Caribbean cooking is so permeated by spicy, irresistible rhythms and piquant, intoxicating horn riffs that it is now standard fare in the discos - and thus one of the most important new ingredients in the stew that it pop music in the late '70s.

The major record companies, always on the lookout for what they hope will be "the next big thing," are betting the whites, blacks and Latins alike will keep on dancing. CBS Records earlier this month signed salsa star Eddie Palimieri, who is scheduled to appear at Carter Barron Amphitheater Aug. 7, to a million-dollar-plus contract, and has already issued two albums by the Fania All-Stars.

Ray Barretto, another major salsa figure, now records for Atlantic Records, the same label that has deals with Led Zeppelin, the Rolling Stones and Crosby, Stills and Nash. El Gran Combo and Willie Colon, two other salsa acts popular in New York and the Caribbean, have had several offers since completing successful tours of the West Coast and Japan.

"Salsa is the hottest item there is in pop music right now," says Rene Lope zof Salsoul Records, who came down from New York to act as a judge in yesterday's competition among 14 local salsa and folklorico groups. "Every major company is now looking for its own salsa band."

Had they come looking at Community West Park yesterday afternoon, they would have encountered several likely candidates. Although the seven hours of Latin music included everything from traditional Mexican ranchero groups to a Brazilian quintet called the Sambistas do Rio, salsa ensembles such as Maria y sus Magnifico sand Tulio Arias y su Orquestra Tipica were clearly the crowd's favorites.

The weather was hot, but the music was even hotter. The powerful rhythms and bold brass lines of "Maria and Her Magnificents" had many of the 500 or so onlookers dancing in the harsh afternoon sun even as they munched on fried plaintains and sipped ice-cold beers. Nearby, musicians from other groups pounded out additional accompaniment on their own congas and timbales and shouted out encouragement in Spanish.

"Salsa has become a unifying element in the Latin community." says Lopez, a member of the NEA Folk and Ethnic panel and the African Diaspora advisory group at the Smithsonian Institution. "It began as a Cuban music interpreted by New York bands, and they injected elements from Puerto Rican and Dominican culture and gave the music its own sound."

From New York and San Juan, the music has spread to Chicago, Los Angeles. Texas and south across the border. "As young Latins relocate," says Lopez, "they take the music with them. There's not that much action in Miami, but I was in Panama and Venuezuela just last month, and salsa is just exploding there. The same thing in Mexico."

Here in Washington, there is also a burgeoning salsa scene. Rene Fabrega, a 23-year-old Panamanian who two years ago was complaning that he had to go to New York if he wanted to hear salsa, now plays the music himself as one of several percussionists in Maria and Her magnificents. "We work fairly steadily," he says. "We don't make a lot of money, but we're going to be playing at a big dance here in a few weeks."

WMAL disc jockey Felix Grant, one of the judges, planned to tape "some of this stuff and use it on my show." Two Latin women standing near him, one in a "Hot Salsa" T-shirt, the other in a "Kiss Me. I'm Puerto Rican" T-shirt, apparently had the same idea: Both were holding tape recorders above their heads, thrusting them toward the music.

"No, hay nada americano, no hay nada importado aqui," festival organizer Jose Suerio told the crowd. "There is nothing American, nothing imported here. This is our thing."

Other events in the Festival Hispanoamericano include film, theater, dance and culinary events. The Festival del Cine Latino begins today at the Wilson Center at 8 p.m. and will include showings of Mexican, Argenine and Brazilian films: dance and theater events will be held Saturday and Sunday at Kalorama Park.

In addition, a "Hispanic Senior Citizens Program" will be offered Wednesday and a "Hispanic Women's Program" on Thursday. The festival will conclude Sunday with a Hispanic American Parade and Carnaval in Adams Morgan.