'Enthusiasm,' by Polly Shulman and 'Twilight,' by Stephenie Meyer

ENTHUSIASM

By Polly Shulman.

198 pp. G. P. Putnam's Sons.

$15.99. (Ages 12 and up)

TWILIGHT

By Stephenie Meyer.

498 pp. Megan Tingley Books/

Little, Brown & Company. $17.99.

(Ages 12 and up)

In this age of young-adult problem novels full of alcohol, drugs, date rape, obscenities and piercings, it's startling to come upon a story that's not only cheerfully upbeat but even a little anachronistic. Polly Shulman's "Enthusiasm," her first novel, brims over with unironical wholesomeness. It begins as Ashleigh Rossi, a sophomore at Byzantium High School, prevails upon her best friend and next-door neighbor, Julie Lefkowitz, to share her current obsession with Jane Austen. Ashleigh, a bit of a weirdo, is determined to speak, dress and act as much like an Austen character as possible.

The girls decide to crash a dance at Forefield, an exclusive boys' school, dressed like characters out of an Austen novel. But when they arrive without escorts they are stopped at the door. To the rescue, conveniently but improbably, come two Forefield boys, the mysterious Charles Grandison Parr and his friend and affable foil, Edgar Downing. Yes, Mr. Darcy and Mr. Bingley have morphed into teenage gallants.

"Enthusiasm," like "Pride and Prejudice," bubbles over with romantic misunderstandings and comic confusion, as when Parr leaves an anonymous sonnet -- a surprisingly good one -- nailed to a tree below Julie's window. Too bad she doesn't notice that the poem is an acrostic that spells out her name ("Just let me wait a little while longer/ Under your window in the quiet snow . . .") and thinks it was meant for Ashleigh. But eventually, true love finds true love, and everyone ends up with his or her destined partner.

With so tidy a happy ending, "Enthusiasm" might fairly be described as escapist fantasy. The literary allusions throughout add a sense of fun and frothiness. As a plot point, however, Julie's obtuseness to Parr's obvious infatuation with her seems a bit forced. Teenage girls who are serious Jane Austen fans will be too advanced for this story, but it might be just the book for a less sophisticated 12- or 13-year-old reader who dreams of romance with a dashing admirer.