"Frankly, the general impression of children's theater is that it's not very good -- dog and pony shows -- not too much substance," says Carole Sullivan, director of Programs for Children and Youth at the Kennedy Center.

"What makes a good performance is for the plays to be designed well and played well, for the mime to be truly mime, and not just the clown who does birthday parties. And the kids must be shown seriously as human beings -- with all their differences."

This weekend Washington gets a taste of the new and improved when the Kennedy Center hosts the 10th International Showcase of Performing Arts for Young People, designed by the Professional Children's Theater Presenters and Producers to promote professional, quality performances for audiences of kindergarten through high school age.

During the two-day event each of the 16 groups, selected from more than 100 applicants from the United States and Canada, has 45 minutes to dazzle an audience that ranges, in addition to children, from booking agents to educators. Along with the performances are numerous exhibition booths for other groups unable to attend. This year there will be 60 in the Kennedy Center Atrium.

"It's wonderful," says Linda Di Gabriele, a 10-year participant and a director of the Asolo Touring Theater. "It produces excellent quality, and gives both producers and presenters the opportunity to see what new material is available. The adults just drop the small people off and don't know what they're missing," says Di Gabrielle. "These plays are wonderful. They deal with the relevant, like family problems, not in a bludgeoning fashion, but in a wonderful way ... You have to show children what's really good so they will go on and enjoy the arts."

Showcase performances are Friday and Saturday. Registration is $65 per person, plus $30 extra for the Saturday night dinner and dance banquet. For information, call 254-7168.