"Uptown Saturday Night" is essentially a put-on, but it's so full of good humor and, when the humor goes flat, of such high spirits that it reduces movie criticism to the status of a most nonessential craft.

The star as well as director of "Uptown Saturday Night" is Sidney Poitier, a man whose way with comedy is reminiscent of Stanley Kramer's in "It's a Mad, Mad, Mad, Mad World." It's less instinctive than acquisitive. He himself can't make anyone laugh but he knows people who can. Mr. Poitier has had the good sense to hire a lot of exceptionally talented and funny people, including Richard Wesley, who wrote the screenplay for "Uptown Saturday Night."

The film combines blunt, rollicking observations on life—the kind favored by black comedians—with the sort of fabulous narrative that has always been a staple of American comedy, from today's Woody Allen back through silent comedy to frontier literature.

Until recently true black comedy (not to be confused with black humor) has been something of an unknown frontier for most Americans who didn't have access to Harlem's Apollo Theater, Moms Mabley, Redd Foxx and the other headliners. Today, of course, Moms, Redd and the others are television headliners, and it's now apparent that a lot of the comedy of Freeman Gosden and Charles Correll (Amos and Andy) was a good deal more witty and accurate than it was fashionable to admit in the nineteen-fifties and sixties.

"Uptown Saturday Night" is an exuberant black joke that utilizes many of the stereotypical attitudes that only black writers, directors and actors can decently get away with. You've never seen so much eye-popping fear and unwarranted braggadocio used in the service of laughs. Yet the result is not a put-down comedy but a cheerful jape that has the effect of liberating all of us from our hangups.

"Uptown Saturday Night" once it gets started (and that takes a bit of time), is about a pair of stupendously ill-equipped innocents, Steve Jackson …, a factory worker, and Wardell Franklin …, a taxi driver, who set out to recover a winning lottery ticket contained in a wallet stolen during the pair's one and only visit to a fancy black after-hours club.

The course of their search takes them through a gallery of rogues, dead-beats and affable con-artists….

Mr. Poitier's intelligence and taste are most noticeable in the film's casting, in the leeway he gives his actors, and in his ability at times to make himself seem physically small and downright intimidated. For a man of his stature, that cannot be easy.

The title of the film refers to neither a time nor a place (the setting seems to be Los Angeles where, as far as I know, there is no uptown). It defines, instead, a film fantasy in which fun needn't have boring consequences, in which gangsters shoot it out without anyone's getting bloodied up, and in which it's possible to have a high old time without fear of a hangover.