Jeffrey Blitz knows adolescent angst.

Having directed 2002’s “Spellbound,” the charming, Oscar-nominated documentary about the kids who train for the National Spelling Bee, he makes his feature debut with “Rocket Science,” a small gem about the overachieving misfits who populate a New Jersey high school debate competition.

One in particular — the goofy, gangly Hal Hefner, who can barely get through his resolution because his stutter is so paralyzing — is based on Blitz’s own stuttering problem growing up. Maybe because the material is so personal, or maybe because he just has a great ear, writer-director Blitz never condescends to his characters in the manner of “Napoleon Dynamite” or “Eagle vs. Shark,” two independent comedies to which “Rocket Science” has been compared.

He’s created full, complex people and placed them in relatable, unpredictable situations — and, for the most part, resists the urge to get sentimental. In the truths it depicts, “Rocket Science” has more in common with the far more commercial hit “Superbad,” complete with an awkward, drunken expression of unrequited love. It’s the only movie you’ll see this summer (if not all year) that has the imagination to combine the Kama Sutra, the Violent Femmes, a projectile cello and an impromptu gropefest in the janitor’s closet.

Hal is in the middle of all these adventures, and the lanky, blue-eyed Reece Daniel Thompson makes him an easy underdog to root for in his first leading film role. It’s not that Hal stutters all the time — on the contrary, he can express himself quite intelligently and incisively. It’s just that there’s no way to turn it on or off. (A vaguely knowledgeable school therapist tells Hal it’s too bad he isn’t hyperactive — then he’d really be able to work magic with him.)

Once the fiercely articulate Ginny Ryerson (Anna Kendrick) invites him to join the debate team, he finds an opportunity to beat this problem — and hopefully all the problems in his life — once and for all.

At the start of our year with Hal, we see his dad (Denis O’Hare) walk out on his mom (Lisbeth Bartlett). We see his obsessive-compulsive, kleptomaniac older brother, Earl (the hilariously weird Vincent Piazza) torment him incessantly. And we see Mom take up with Pete (Steve Park), the friendly Korean judge down the street who happens to be the father of Hal’s only friend, Heston (the sweetly nerdy Aaron Yoo, Shia LaBeouf’s pal in “Disturbia”).

Through all these tumultuous changes, the thing that keeps Hal going is the promise of arguing alongside Ginny, the queen bee who recruits him to be her partner after the school’s superstar debater, Ben (Nicholas D’Agosto), freezes on stage in the middle of the state championships. And who could say no? She’s a force of nature — brilliantly bossy, eloquently verbal and unflappably convinced of her own capabilities. (Kendrick, who was a Tony Award nominee at just 12 years old, makes a potentially obnoxious character pretty irresistible.)

Blitz refrains from foisting the obligatory on-stage moment of redemption upon us; at the same time, there’s a beautiful, natural place for him to end things, and he keeps going. And we probably didn’t need repeated voiceover visits from a wise narrator to provide perspective. Nevertheless, he continues to make a case for himself as a filmmaker with rich, realistic stories to tell.

“Rocket Science,” a Picturehouse release, is rated R for some language and sexual material. Running time: 98 minutes. Three stars out of four.

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Motion Picture Association of America rating definitions:

G — General audiences. All ages admitted.

PG — Parental guidance suggested. Some material may not be suitable for children.

PG-13 — Special parental guidance strongly suggested for children under 13. Some material may be inappropriate for young children.

R — Restricted. Under 17 requires accompanying parent or adult guardian.

NC-17 — No one under 17 admitted.