The 2001 film Legally Blonde, based on Amanda Brown’s novel and starring an engaging Reese Witherspoon as the unlikeliest of Harvard Law School students, couldn’t quite decide whether it wanted to exploit or explode the dumb-blonde, sorority-queen stereotype. The musical adaptation, which hit Broadway in 2007 and is now playing the Walnut Street Theatre’s main stage, has much the same problem.

Legally Blonde: The Musical isn’t clear on whether academic smarts, a dopily seductive move called the “bend-and-snap,” or wide-eyed flirtatiousness is the surest route to a man’s heart. Nor, for that matter, whether a young woman should be aiming mainly for that heart in the first place — as opposed to acing a murder trial, becoming class valedictorian, and plotting a legal career.

But in the end, this being a musical comedy — and a particularly frothy one at that — no hard choice is really necessary for its heroine. Southern California fashion merchandising major Elle Woods (a supremely likable Kathryn Brunner) gets to have it all: marriage, career, the confidence to be herself, the thrill of transforming herself into something more.

If Heather Hach’s book battles incoherence and some of Laurence O’Keefe and Nell Benjamin’s lyrics are equally baffling (“Chip on My Shoulder” as an inspirational anthem?), the Walnut’s brassy, lively production goes a long way toward anesthetizing the pain.

Director-choreographer Richard Stafford (who also helmed last season’s cartoonish Mamma Mia! for the Walnut) excels at comic choreography: a prison jump-rope number (“Whipped into Shape”), a Riverdance parody, a Greek chorus of sorority girls.

Stafford has assembled a first-rate cast of Broadway and national tour veterans (and two well-trained dogs) to support Brunner’s star turn. Paul Schoeffler, as Professor Callahan, and Rebecca Robbins, as the salon stylist Paulette, are standouts, making the most of their character-defining numbers.

Callahan’s credo is “Blood in the Water,” a Hobbesian (and Socratic) hymn to legal ruthlessness. Paulette’s is “Ireland,” a ballad about the Irish love she was hoping to find. (Costume designer Kurt Alger gives her a series of snazzy jeans-based looks that are just right.)

Elle’s love interests are Warner Huntington III, played by the vocally talented Sean Thompson, less prepster than lizard, and the scruffy, dorky but good-hearted Emmett Forrest (Elliott Styles).

A law school graduate, Emmett is somewhat mysteriously still hanging around Harvard Law (as evoked by scenic designer Peter Barbieri’s redbrick walls, emblazoned with the Veritas emblem). Emmett helps Elle discard some of the trappings of sorority life and find her law books. She, in turn, buys him a good suit — because not only men have money, and not only women need to keep up appearances.

THEATER REVIEW

Legally Blonde: The Musical

Through July 14 at the Walnut Street Theatre, 825 Walnut St.

Tickets: $25-$97, with premium tickets $175.

Information: 215-574-3550 or 800-982-2787, walnutstreettheatre.org