I magine the surprise of a first-time visitor who happens past Lincoln Center on an early summer night. Live music soars from a bandstand in the center of the Josie Robertson Plaza, and for almost as far as the eye can see, people are dancing. The songs move at a brisk clip, lasting just three or four minutes so dancers can switch partners or catch their breath. When the band needs a break, a deejay takes over, and Midsummer Night Swing, the biggest, most exuberant outdoor dance party in New York, whirls on without missing a beat.

For thousands of dance enthusiasts, summer in New York begins on the opening night of Lincoln Center's annual, five-week danceathon under the stars. Since 1989 Midsummer Night Swing has attracted more than 100,000 dancers and spectators each year. The foremost dance bands from around the world fill the warm summer air with swing and salsa, tango and the Texas two-step. Everyone is welcome, no dance experience is required. For anyone unsure of the steps, teachers from the city's top dance studios offer free lessons.

This year Midsummer Night Swing, which runs from June 25 through July 26, presents an inviting lineup of bands that offer the twin qualities audiences request most‹danceability and diversity. "The music should make people want to get up and dance all night," says Wendy Magro, producer of the festival. The bands embrace a breathtaking spectrum of styles and sounds. Swing and Latin orchestras reign most evenings, but no two bands are alike. Jump, West Coast, uptown, Texas, and hi-de-ho are just a few of the styles to get audiences swinging. Latin evenings showcase tango, son, merengue tipico, mambo, Latin soul, and multiple strains of salsa. This year's specialty programs include an evening of Irish Céilì, a Brazilian night spotlighting dances from the nightclubs of Rio, a disco night, and a Zydeco evening that will combine the speedy Louisiana two-step with funky blues. A special highlight is Midsummer Night Swing's first dance contest, Wednesday, July 9, when Lincoln Center hosts the East Coast Vaseline Intensive Care "Smooth Moves" Dance Competition, judged by renowned New York City dance champions and teachers Melanie LaPatin and Tony Meredith. The contest, which will be free of charge, will take place before the regular dancing begins at 6:15 p.m. On July 23 the winners will go toe to toe with the "Smooth Moves" Dance Competition winners from the West Coast for a final dance-off. May the best Coast win!

The Festival's opening night features the boisterous Buster Poindexter Band, the jump-swing group launched in the 1980s by rock singer David Johansen. "I live right around the corner," says Johansen, "so I know the festival's a lot of fun." In addition to a danceable grab bag of swing, Latin swing, jump blues, and soca, Johansen expects the band to perform its signature novelty songs, such as "Who Threw the Whiskey Down the Well."

Buster Poindexter will be performing at Midsummer Night Swing for the first time, but many bands are festival veterans. The house band, Wynton Marsalis and the Lincoln Center Jazz Orchestra, brings back its distinctive jazz and swing on July 2. Bronx trumpeter Jimmy Bosch returns on June 27. And for the 15th time, swing artist Illinois Jacquet and his Big Band will close the festival.

If this year's festival had a theme, it would be a salute to the accordion. At least one accordion-based band plays each week‹in the week of July 16, there are three. "I kept hearing terrific bands with accordions," says Magro, who talked with dancers, listened to dozens of CDs, and frequented dance clubs to select the festival's music. The accordion has had an impact upon every style of music, she explains, thanks to German, Slavic, and Polish immigrants who brought the instrument to the United States, Mexico, the Dominican Republic, and Peru.

The Texas-based accordion band Brave Combo offers music for polka and cumbia, a Mexican style of polka, on July 18. Geno Delafose and French Rockin' Boogie, a Louisiana Zydeco band, bring their Cajun accordions to the plaza on July 24. And versatile New York accordionists Will Holshouser and Charles Giordano appear as guests on July 17 with the aptly named Minneapolis-based Café Accordion Orchestra for an evening of sultry Parisian café music‹rumba, bolero, Gypsy swing, and valse musette.

Accordions also feature prominently on tango night, June 26, led by Buenos Aires-born Hector del Curto and the Eternal Tango. Even Céilì master John Whelan, who writes his own Irish jigs and reels, is an accordion wizard, although the guest artist for the July 11 Irish evening is banjo maestro Eric Weissberg, who played "Dueling Banjos" on the sound track for the movie Deliverance.

Also featured this year will be Dominican-born Quebec resident Joaquin Diaz (July 3), who is the leader of his namesake merengue tipico band; Country Music Hall of Famer Hank Thompson of Oklahoma (July 12), whose Brazos Valley Boys band first played Western swing in 1946; and blues and West Coast swing specialists Sugar Ray and The Bluetones (July 19), who hail from Rhode Island.

Hometown acts include the big band Harlem Renaissance Orchestra (June 28), elegant purveyors of uptown swing; Spanish Harlem Orchestra (July 5), specializing in salsa, Latin sour, and boogaloo; and jump blues and swing artists Ron Sunshine and Full Swing (July 9). Also from New York are the Cab Calloway Orchestra (July 10), the hot swing band directed by C. Calloway Brooks, grandson of the band's legendary founder; and Son Sublime (July 23), a son, mambo, and cha-cha band.

Indeed, even the principal performers with Cliff Korman's Gafieira Dance Club (July 25), all born in Rio de Janeiro, now live in New York. Among the cutting-edge Brazilian dances they will play are Forro, a zippy, rural accordion-based dance, and the slow, sensual Baiao. "There's a big Brazilian population in New York, but a lot of people will be learning these dances for the first time," says Magro. And that, of course, is what Midsummer Night Swing is all about.

Terry Trucco is a freelance writer specializing in dance and design.