Ford's Theatre, which hasn't had much luck fostering new shows of late, has fallen back on old reliables this season: James Whitmore's "Will Rogers' U.S.A." last month; and starting last night for a run through Nov. 11, that spiffy little satire of small-town life, "Greater Tuna."

You can't exactly applaud Ford's for venturing out on a limb -- "Greater Tuna" already proved itself a big hit at the Kennedy Center 14 months ago -- but you can understand the necessity for the booking. Ford's original spring musical, "On Shiloh Hill," all but wiped out the theater's budget. Comes a time when box office must be served, and "Greater Tuna" serves it well.

The play ushers us through a day in the life of Tuna, the third smallest town in Texas and a bastion of bigotry and narrow-mindedness. It's the sort of place where the Lions Club is viewed as suspiciously liberal; where the annual high school essay contest produces entries titled "Human Rights -- Why Bother?" and "Living With Radiation"; and where "Roots" is being removed from the library because "it only shows one side of the slavery issue."

Starting with the morning broadcast from radio station OKKK, wandering in and out of the various households, dropping by the Baptist Church, moseying out to the underpass where the garbage is dumped (and UFOs appear to some), and finally returning to the radio station for the late-night sign-off and "The Star-Spangled Banner," the show paints a wickedly amusing panorama of conservative mores. To two enormously gifted quick-change actors, Jaston Williams and Joe Sears -- falls the task of incarnating 20 or so of Tuna's more colorful denizens, male and female. And they do so with a deadly accuracy that would be cruel if it weren't qualified by real affection for these moral midgets and their woebegone lives.

There's Bertha Bumiller, the book-burner, trapped in a lousy marriage and saddled with three impossible kids and "eight to 10" dogs. There's Reverend Spikes, who can't open his mouth that a cliche' doesn't tumble out. And ineffably sweet Petey Fisk, who as the head of the Greater Tuna Humane Society, is out to save every stray mutt, cat, duck (and a snake named Ruth) that comes his way.

The town judge is found dead in a one-piece Dale Evans swimsuit, to the secret delight of Aunt Pearl Burras, who was jilted by him as a young girl and vowed then and there she would sing over his grave. ("Judge," she says, eying his waxy corpse with quiet satisfaction, "I feel a song coming on.") Bitter Didi Snavely presides over the town's used weapons store, while her doughy husband plays his fiddle idly under the stars. Some of the characters are woven in and out of the proceedings; others simply pass by once. But Sears and Williams, eschewing parody, treat them all as full-bodied human beings.

The humor of "Greater Tuna" will leap out at you. The actors, who wrote the script in collaboration with director Ed Howard, clearly find these people as funny of manner as they are ludicrous of dress. But what you may not expect is the tone of ruefulness that also courses through the show. As effortlessly as they seem to change costumes, Williams and Sears can suddenly turn a character inside out and show you his aching heart.

If Ford's is going to fish its attractions out of the past (a revival of "Godspell" is set for spring), better "Greater Tuna" than many. Modest as its dimensions are, it's a whale of an entertainment.