The all-American town of Blaine, Missouri, is celebrating its 150th anniversary. To mark the occasion, it turns to Corky St. Clair (Guest in a swishy performance that might offend some) to put together a show. Corky, a Broadway expatriate who's found stature and clout in his adopted hometown with his innovative productions of Barefoot in the Park and Backdraft, responds with a musical salute to the town's history called Red, White, and Blaine. Among its high points are the founding of Blaine by the eponymous explorer who thought it was California, a visit from President McKinley that made the town the Stool Capital of the World, and a pre-Roswell UFO incident that left a surviving witness with no feeling in his buttocks every day afterward at the exact time of his alleged abduction.

In short, Blaine is a composite of every bogus claim, dubious achievement, and jaundiced hope of the American heartland. To bring this to life on the stage, St. Clair and his collaborator, the high-school music teacher Lloyd Miller (Bob Balaban in a brilliant rendition of deferential deflated ego) audition the local talent. Ron Albertson (a joyfully smarmy Fred Willard) and his wife, Sheila (a sourly flaky Catherine O'Hara), the local travel agents who pride themselves on never having left town, are a cinch to be cast. Veterans of previous St. Clair extravaganzas, they wow Corky and a somewhat more dubious Lloyd with their tuneless rendition of "Midnight at the Oasis."

The rest are newcomers. There's Dr. Pearl (Eugene Levy in a tour de force of ingenuous fecklessness), the stiff town dentist, who pumps new magic into a Stephen Foster medley and old Johnny Carson routines. Clifford Wooley (Lewis Arquette), a retired taxidermist, takes readily to the role of the show's hobo narrator ("Don't get me started on the subject of beans!"). Less distinctive are Matt Keeslar as the local hunk mechanic Johnny Savage, whom Corky takes a special interest in grooming, and the ubiquitous Parker Posey, who's nondescript and uncomfortable as Libby Mae Brown, the Dairy Queen counter girl.

As in every backstage musical, the troupers of Guffman are challenged by misfortune: the council refuses to cough up the $100,000 budget Corky asks for, and Johnny Savage doesn't break a leg but does get cold feet at the last minute. But they have a dream to sustain them. The show serves not just to honor the past but to embrace the future. Through his New York contacts, Corky has arranged an opening-night visit from Guffman, a Broadway representative.

Ludicrous though the show and its makers are, Guest so deftly balances the film's tone between farce and pathos that their success matters and their dream, however tawdry, has validity. Through the broader comic strokes shine subtle and poignant nuances of character and conflict: the power struggle between the cocksure Corky and the passive-aggressive Lloyd, the pseudo-urbanity and not-so-quiet desperation of the Albertsons, the naive purity of Dr. Pearl's drive to entertain and his appalling lack of talent. Most important, Guest doesn't let his players down in the clinch; the show, though bizarrely hoky, is actually not bad.

As the Beckett-like title suggests, Waiting for Guffman has its moments of disillusionment -- the climactic scene is shockingly heart-rending. Guest respects his characters and his small town enough not to let them live happily ever after. He's also smart enough to leave the audience laughing. Whatever you do, don't depart before the final scene, in which St. Clair shares his show-biz memorabilia collection. Guffman may not be worth waiting for, but the My Dinner with Andre action figures are.