The hero of Kevin Smith's third film is smart, confident, well versed in pop trivia and ready for Socratic discussion of any feasible issue, no matter how petty or small. So Holden (Ben Affleck) has a lot in common with the film maker, whose "Chasing Amy" reignites the energy of "Clerks" and puts Mr. Smith's career back on track. After the literally sophomoric dawdling of his more elaborate "Mallrats," Mr. Smith retrieves some of the spare look and basic cleverness of his celebrated first feature. He also expands that style to accommodate genuine emotions. Still showing his touch for garrulous, hair-splitting conversation, Mr. Smith engages his characters in a bright, spirited demonstration of just how difficult modern love can be. Total candor, shifting sexual orientations and an atmosphere of teasing, freewheeling argument make "Chasing Amy" a spiky comedy with engaging honesty at its core. In his own roundabout way, Mr. Smith identifies sexual conundrums that movies haven't often dealt with before.

As played with wonderful ease by Mr. Affleck, Holden is just the right levelheaeded man for such matters. he is a comic-book artist. (Mr. Smith's brand of auteurism still celebrates boyishness verging humorously on arrested development.) But Holden also seems worldly and self-possessed. Certainly he is the grown-up in debates with his sidekick, Banky (played by Jason Lee, a skateboarding star turned actor who was the best thing in "Mallrats" and is again darkly funny here). And he has a cool, contained manner that suggests he has seen everything, though it turns out he hasn't seen anything quite like Alyssa (Joey Laruen Adams ) before.

This bitsy-voiced blond first turns up at a lecture where Holden's effeminate and very funny friend, Hooper (Dwight Ewell), is pretending to be a macho black militant as he attacks racism in the "Star Wars" trilogy. (Hooper's riff, which insists that the Jedi conquest of the galaxy is a form of white gentrification, is typical of the enjoyable little sidelines that "Chasing Amy" offers.) And when Holden begins sparring with Alyssa, he finds her a quick-witted, mischievous intellectually match. Then, as he starts finding himself sexually attracted to her, he discovers there's a hitch. Alyssa likes women and has no sexual interest in men. The stubborn style of "Chasing Amy" makes this a beginning , not an end. Holden and Alyssa are off and running in a set of conversations that artfully challenge their basic assumptions about sex and love. Banky, who makes anti-gay jokes and seems to want Holden to himself, is furious about this and complains helplessly from the sidelines. But the film does find time to draw in Banky for one raw, uproarious three-way boasting match about physical injuries acquired during oral sex. In its later stages, "Chasing Amy" lets an affair develop between Holden and Alyssa in ways that sets their worst prejudices and jealousies in motion. The film gets rockier here, since Ms. Adams fares better with frank, jousting dialogue than with shrill monologues that lay bare her emotions. Mr. Affleck, who like Matt Dillon combines suave good looks with cool comic timing, has to work hard to seem entirely floored by these outbursts. Then along comes the cavalry: Jay (The irresistible, jive-spouting Jason Mewes) and Silent Bob (Mr. Smith), the two dudes from "Clerks" who have become the stars of Holden's comics and are still wandering through the Smith oeuvre. As Bob tells the anecdote that explains the title, he gives "Chasing Amy" an edge of regret beneath its torrent of small talk.

As "Chasing Amy " redefines the boy-meets girl formula for a culture where anything goes, including perhaps another boy or girl, it thrives on Mr. Smith's dry humor and unruffled style make a good antidote to gender chaos. Music by David Pirner contributes to the film's loose, inviting mood.