"Kids on the Block" -- tonight at 8 on Channel 20 -- provides a brief but realistic and benign departure in children's programming. The half-hour program is a showcase for a troupe of disadvantaged and minority children played by puppets; through the puppets, actors speak candidly and revealingly about their conditions.

Ranging from blindness to paralysis, the handicaps become humanized and manageable. Producer Peggy Sullivan has made the program informative and less preachy than it might have been.

The puppets seen on the program were discovered for television after a successful run in Washington. At times one may wish that the roles were being played by real actors, but there is a studio audience that includes real children, handicapped and otherwise. It isn't easy to make puppets work on TV, but "Kits on the Block" is successful most of the time.

In one of the best segments of the show, youngsters ask the puppets about their physical handicaps. To a blind puppet: "If you're blind, how come you wear glasses?" To a quadraplegic: "How do you use the bathroom?" When the puppets introduce themselves, the quadraplegic sings out, "I'm the only kid with braces who's chewing bubble gum," and a girl says to her speechless friend who uses sign language that she can talk with her mouth full.

The blind puppet notes, more than once, that he has the unique advantage of not being afraid of the dark.

In the program's most effective, least cloying sequence, one of the puppets reluctantly goes on a telethon as a poster child, and is besieged by an obnoxious, condescending host named Richie Carmel, who bears a resemblance to Jerry Lewis. And moments of sadness are followed by moments of laughter. Kids will more than likely enjoy this show; it has social merit and serves as a welcome alternative to the cacophony of cartoons.