Kyle Jarrow tends to bounce more than walk, to bubble rather than speak. He has a habit of writing notes to himself on the back of his hand. In a 2003 preview article on his rock musical “President Harding Is a Rock Star,” the New Yorker likened him to Dennis the Menace.

Don’t let his spiky hair or ebullient grin fool you, though; beneath those thick hipster glasses, there’s something downright serious brewing. Since graduating from Yale in 2001, the 25-year-old playwright and musician has already had four major productions of his plays mounted in New York City, won an Obie Award, and built a steady following for his five-person glam-rock band, the Fabulous Entourage, a group that can count Los Angeles’s Viper Room and New York’s Knitting Factory among its impressive list of bookings. (The band is scheduled to perform again April 2 at Sin-e on the Lower East Side.)

Mr. Jarrow’s interests in theater and music came together again in “Gorilla Man,” a play about a teenage boy in search of his half-gorilla father that just finished a run at Performance Space 122. In addition to writing the script and composing the music, Mr. Jarrow served as narrator and eerie musical ringmaster in the show that he calls more “exploded rock show” than musical.

Did he always want to be a rock star?

“I thought I was going to be a poli-sci major when I first got to Yale,” Mr. Jar row said over lunch last week at the Old Town restaurant near Union Square. But he quickly grew disillusioned with classmates who all seemed to be aspiring politicians, and professors who “would always gloss over the religious elements” in discussions of world conflict, choosing to point to economic or territorial issues instead. “People who are going out there and dying believe that they are doing it for a religious reason … and I just felt that was something that political science didn’t know how to deal with.” Mr. Jarrow changed his major to religious studies.

Many of the Fabulous Entourage’s songs have a post-apocalyptic feel to them, and his plays feature individuals grappling with existential questions of what to believe and how to live. “I think that’s the issue of postmodernity,” Mr. Jarrow said excitedly. “I mean, people don’t know how to live anymore. The only segment of society that is not adverse to making any value judgments about how to live is religious organizations.”

Raised by secular parents in Ithaca, N.Y., his father an economics professor and his mother a children’s book author, Mr. Jarrow counts himself among the ranks of the moral relativists. But he admits a touch of wistfulness for a more absolute compass. “Moral relativism is a difficult way to live. In my own life, I find that a troubling issue. I think all my plays are a little bit about that.”

His one-act play “Armless” (which received an award for “overall excellence” at the 2004 New York International Fringe Festival) concerns a man who desperately wants to cut off his own arms. It’s as funny a play as it is shocking. But the question he touches on is really not as absurd as it may seem – if it would make this man happier and not harm anyone else in the process, then should he do it? Would it be morally wrong for him to remove his perfectly healthy limbs? Wrong for those around him to let him do so?

When a friend sent an article about something called Body Identity Integrity Disorder, the subject struck Mr. Jarrow as “very thematically resonant – the paradox of trying to achieve ‘completeness,’ but cutting off a piece of oneself.” He decided to write about it when he realized that he couldn’t decide if the surgery these sufferers want should be allowed. “I’ve found that uncertainty and the feeling of being unsettled are great places to write from,” he said. “Armless” responds to the question with compassion, but not with an answer.

“It used to be that people would tell you how to live, and you’d live that way because if you didn’t, you’d go to hell,” he said. The shift in the religious teachings of today, Mr. Jarrow feels, is toward systems that promise rewards in this life, like money or peace.

He explored this trend in his 2003 off-Broadway hit “A Very Merry Unauthorized Children’s Scientology Pageant,” in which he used a cast of 8- to 12-year-olds to enact the history and teachings of L. Ron Hubbard, the founder of the controversial organization. The show skewered Scientology, but not in an easy, obvious way. One of its final moments, in which a young boy stands alone onstage and sings about profound alienation, was absolutely haunting – no matter how one might feel about Scientology.

The New York Times called it “a spooky, sharp-toothed smile of a show,” and along with the director, Alex Timbers, Mr. Jarrow received an Obie Award for it. His rapidly growing body of work seems to prove that just because something is entertaining doesn’t mean it’s trivial. But despite all his success, Mr. Jarrow doesn’t see a new theatrical show on the immediate horizon.

“Getting the money for ‘Gorilla Man’ almost killed me. I spent a year running after money,” he said. In the end, most of the funding came from private donations – and in a city of art financed by trust funds, he’s quick to point out that none of that money came from his family. “It was all from people we knew who believed in the project, thank God. But it was really hard, and I can’t do it again.”

He is also frustrated by the limited demographics that theater appeals to. “The Scientology pageant, at most, maybe 3,000 people saw it – that’s nothing!” So the possibility of reaching more people – and different kinds of people – through the mediums of television and film is an enticing one. He’s currently at work on two screenplays and a handful of ideas for television, and he expresses cautious excitement about the artistic possibilities the new mediums might offer.

His dream, though, is to record an album with his band and go on tour. But he worries about the money that stands between him and that dream. A few weeks ago, the Fabulous Entourage played a gig at Joe’s Pub at which they had to turn away 150 people, and there has been interest from several record labels. But without the money to put together a good demo, Mr. Jarrow worries that the interest will dissipate.

“I get down on myself all the time,” he said, suddenly sounding much older and looking bone-tired. “It’s really tough not having money and not knowing from day to day what’s going to happen.” Then, in the next moment, he put both hands on the table and spoke from that uneasy place between believer and cynic. “But I have to remind myself, I would not trade my life for anybody’s. I mean … I’m just so lucky. And I have to struggle every day to remind myself of that.”