Normally, filmmakers shouldn't be encouraged to make the same movie twice, but Christopher Guest has recycled the cast and the "mockumentary" format of Waiting For Guffman, switched his fat target from community theater to dog breeding, and pulled off the equally hilarious Best In Show. As with Guffman and This Is Spinal Tap, Guest has a rare ability to drape heavy improvisation around a skeletal script without letting the individual sketches, or the comedy as a whole, fall slack. He's also come to specialize in affectionate caricature, parodying the small-scale hopes and dreams of Middle America by inflating them far past the point where it might seem condescending, as some critics have charged. Slight and unpretentious, Best In Show has no higher ambition than to string together enough funny gags to keep from collapsing over the course of 90 minutes, but under those agreeably modest standards, it's an unbridled success. Building to the Mayflower Kennel Club Dog Show in Philadelphia, Guest and co-writer Eugene Levy pair off four couples and their beloved purebred pets. The funniest of the four are Parker Posey and Michael Hitchcock as intensely neurotic yuppies who dump all their marital baggage on a demoralized Weimaraner. If the other dogs aren't psychologically affected by their owners, they almost always look like them. Doting over a Norwich terrier, Catherine O'Hara and Levy play a woman with an endless sexual history and a doltish husband who was literally born with two left feet. An amusing caricature of a caricature of a gay couple, John Michael Higgins and Michael McKean over-primp a toy Shih Tzu while millionaire trophy wife Jennifer Coolidge and high-strung trainer Jane Lynch carry the favored white poodle. With yuppies, nerds, bluebloods, and gays already covered, Guest casts himself as the lone hick, a slow-witted fly-shop owner who arrives with a mopey bloodhound in tow. Considering the crude stereotypes on display, Best In Show risks being narrow and mean-spirited, but the mostly terrific cast brings enough generosity and warmth to make it seem more inclusive than it might have otherwise. And, just when the jokes start to flag, Fred Willard appears in a sidesplitting turn as a boorish American announcer who exasperates his polite English counterpart with dim quips—"In some countries, these dogs would be eaten"—and inappropriate baseball metaphors. Best In Show may chart few advances on the Guffman formula, but it has a fine time running in place.