Having seen her parents divorced, her pouty perfectionist sister engaged to a bland country-club preppie and her knocked-up best friend suffer a terrible romantic tragedy, Halley Martin is one high school girl very wary of love.

As played by pop- princess- cum- promising- actress Mandy Moore, she's also a credible Everyteen with a good head on her shoulders, which is what makes her determination to guard her heart a sound basis for "How to Deal," a fluffy slice-of-teen-life drama that strives to raise the bar a little for its often eye-rolling genre.

Adapted from the youth novels "Someone Like You" and "That Summer" by Sarah Dessen, the film is an admirable step up from the superficial, soundtrack-driven tripe usually targeted to the MTV demographic, and Moore's appealing, unaffected authenticity buttresses the story in its weaker passages.

Halley is not a movie teen with cute, prefabricated, "Lizzie Maguire"-ish problems like not being the most popular girl in school, and she's not a tear-jerking charity case like the terminal heroine to which Moore lent emotional veracity in last years maudlin "A Walk to Remember." Halley is sublimely, singularly human.

But while Moore has some depth to work with as an intelligent girl trying to keep her head above her hormones, the same cannot be said of Macon (somber, slim, non-threatening Trent Ford), the hair-in-his-eyes bad-boy-with-a-heart from Central Casting who inevitably enters the picture to test Halley's resolve.

Other supporting characters are equally two-dimensional (Halley's midlife-crisis daddy, played by Peter Gallagher, is a morning-zoo DJ planning an on-air stunt wedding to his traffic girl). But some of the cast members rise above their roles, notably bubbly Alexandra Holden ("The Hot Chick") as the pregnant pal and the always terrific Allison Janney ("The West Wing," "Nurse Betty") as Halley's divorcee mom who tries to stifle her pain and bitterness for the sake of her daughter.

Director Clare Kilner (whose previous features were seen only at a few film festivals) navigates several on-cue soap operatic crises (the pregnancy, a car crash) with a prudence that gives the story a true-to-life undercurrent, which makes up for some of the movie's problems. Besides the stock supporting characters (a cannabis-smoking comic-relief grandma, the sister's uptight future in-laws) there are some emotional inconsistencies (level-headed Halley occasionally blows up at her mom without much cause) and many petty peripheral incongruities (the dad works at a "soft rock" station, yet has rowdy, barking frat-boy fans).

The strength of Moore's performance and Kilner's efforts behind the camera largely outweigh these concerns, but "How to Deal" can't seem to stay faithful to its aspirations of coloring outside the lines of cliché. In the end it heads down the same path as any other chick flick in which The Guy screws up badly, then makes a grandiosely fictional romantic-gesture apology in the last reel.

Halley's reaction to Macon's mea culpa shows she's not a doormat, but instead of sending teenage girls the message that there's more than one fish in the sea, the movie cops out and ultimately conforms to the rose-colored Hollywood template it came so close to breaking.