High school, as we all knew at the time, is life. Life in rehearsal, life before Life, but still, the time of one's greatest agonies and purest exhilarations, when the present is a confused mess but the future a clear beacon.

"Out of the Reach of Children," a new musical just opened at the New Playwrights' Theatre, uses the familiar traumas of American adolescence for an utterly charming, lively five-woman show that proves that small-scale theater can be just as professional and entertaining as any big-time extravaganza.

Despite the clumsy title, which sounds faintly medicinal, the show explores with wit and tenderness the well-worn subject of what happens to five friends in their last year of high school and returns to them seven years after graduation. Author-composer Cornelia Ravenal is a graduate of the National Cathedral School for Girls here, and the milieu of the play is that of the upper-middle-class private school in 1975, where the girls are, as ever, worrying about boys, their weight, their bustlines, their mothers (whom they can't stand), sex and getting into college.

"I've got the upper-middle-class, overprivileged white girl blues," sings the pudgy Ellen Goodman, class clown, at one point. "Why does my mother treat me like a child?" trills the class president, Laura Kelly, as she hangs on to a stuffed animal. Marian Urbanski, the artistic type, models herself after Isadora Duncan and has a terrible reputation. "I don't sleep with every guy in school," she says. "Just the smart ones. With good bodies."

Patty Fisher is the grind, desperate to get into Yale and woefully aware that she is a nerd. Thea Bates is an elegant black model, who left home 2,000 miles away to take a scholarship and leave an unhappy family behind.

Each wrestles with her lack of perfection, her impatience to grow up ("Don't you feel like you'll be 17 forever?" they sing), and the eternal question of who she is. In the first act, they cope with rituals of adolescence like shopping, fighting with best friends, talking all night and keeping or losing their virginity. In the second, more somber act, life has caught up a bit and the scars of mistakes made and disappointments faced are apparent in a series of reunions after college.

Director Fredric Lee and designer Lewis Folden have divided the stage into a set of levels with a separate area for each girl; the girls interact through the inevitable telephones and occasional encounters. Ravenal's music is a kind of rock-flavored Stephen Sondheim. Melody is not her strong suit, but the lyrics are deft and the arrangements are sophisticated and interesting. If anything, there are too many songs (23 plus reprises), and perhaps a few cuts would alleviate the sense of repetitiveness that begins to set in by the second act. But it also must be said that to write, as Ravenal has, a bittersweet song about abortion that is actually moving, is a rare accomplishment, both for her and for Veanne Cox, who sings it.

Since the subject matter is neither original nor profound (plays such as "Vanities" and "Uncommon Women and Others" leap to mind), it is the music and the characters that make this show endearing. Each girl/woman is familiar, someone you knew or someone you were, with all the giddiness, anxiety and aching intensity that is surely a clear memory for almost everyone, regardless of age or sex.

The cast is so uniformly excellent that one forgives the occasional strained note. Melissa Berman shines as the goofy Ellen, flopping around with the eagerness of a puppy, and Caron Tate's cool, repressed Thea is physically and vocally terrific. Veanne Cox as the sultry dancer Marion is equally stunning, a real presence on the stage. Gretchen Weihe has a lovely soprano that is a welcome addition to the vocal mix, and her goody-two-shoes Laura never gets insufferable. Bev Sheehan's Patty undergoes a metamorphosis from an anxious bookworm to a less-anxious lesbian, without ever losing the essential character that she had in high school.

Which is, of course, one of the real points of this musical, despite its proclaimed statements about growing up. That is, you are what you were -- you can get out of high school, but can you ever get the high school out of you?

"Out of the Reach of Children," by Cornelia Ravenal, directed by Fredric Lee, design by Lewis Folden, musical direction by Ed Rejuney, costumes by Jane Phelan, orchestrations by Marc T. Johnson.

With Melissa Berman, Gretchen Weihe, Bev Sheehan, Veanne Cox, Caron Tate.

Musicians: John Buckle, Kurt Carr, Bob Green, Lynn Hertel, Ward Harris, Michael Mendelson, Ed Rejuney.

At the New Playwrights' Theatre through Dec. 23.