Rising admirably above the bubble-gum genre norm, "The Sisterhood of the Traveling Pants" is a smart, charming, superbly acted summer-adventure matinee about four 17-year-old best friends separated for the first time but symbolically linked together by a pair of second-hand jeans they share by mail.

Found to inexplicably fit each of them despite very different body types, the pants become a touchstone as they're sent from friend to friend, giving each girl confidence, good luck or comfort from unexpected hardship just when such encouragement is most needed.

Adapted from the first in a series of popular books by Ann Brashares, the movie has a foundation of coming-of-age clichés, but builds upon it beautifully with three-dimensional characters and honest angst, consternation and joy.

Alexis Bledel ("Gilmore Girls") plays shy, beautiful, lanky Lena, whose vacation in a stereotypical Greek fishing village comes complete with a hunky local (Michael Rady) who rides a Vespa. This is "Sisterhood's" least creative storyline (it even has a "Romeo and Juliet" bent), but Bledel digs for emotional truth and finds it.

Tall, blonde and sporty Blake Lively -- a newcomer worth watching -- plays bold and flirtatiously forward Bridget, who loses her virginity by seducing a 20-something coach (Mike Vogel) at a seaside soccer camp in Baja California, grasping for intimacy in the wake of her mother's suicide and her father's indifference.

Outspoken yet vulnerable, plus-sized Carmen (talented America Ferrera from "Real Women Have Curves") spends her summer feeling like an outsider as her father (Bradley Whitford) prepares to wed a WASPy, halcyon minivan mom (Nancy Travis) with a pair of perfect, towheaded teenagers. Ferrera has the movie's most gut-wrenching breakdown as she confronts Dad about his failure even to tell her about his fiancée before she came to visit.

But director Ken Kwapis ("He Said, She Said") channels the most emotional energy into the story of punky, cynical Tibby (Amber Tamblyn from "Joan of Arcadia"), a part-time drug-store drone bitterly stuck at home and making a "suckumentary" about suburban monotony. Tamblyn gives raw heart to a reluctant friendship with a 12-year-old neighbor (Jena Boyd) that takes a tragic, tearjerking turn.

"Sisterhood" nails its emotional tone and its character depth so well that it's all the more disappointing when the picture does fall back on contrivances, like the cheesy opening voice-over, a circle-of-candles pants-christening ceremony, and its overly simplistic attempts to wax philosophical.

But because it's an energetic, competently made film (vividly colorful and creative production design, good transitional editing) that lets its young characters make real mistakes and find real trouble as they transition realistically into a larger world, "Sisterhood" is exponentially more earnest, affecting and credible than 90 percent of movies aimed at teenage girls -- and it's universal enough to appeal to women (and even men) in their 20s as well.