HOLLYWOOD — Backstage at Hollywood's El Capitan Theatre, the comedian Sarah Silverman is kneeling on the floor of her boyfriend's crowded office, looking rapturously at his image on a flat-screen monitor. She is wearing low-slung jeans, a worn navy crewneck sweater over a baseball T-shirt and sneakers. Her silky black hair is pulled into a ponytail. She is very pretty, almost angelic, looking more like a fresh-scrubbed college kid than the 34-year-old show-biz vet that she is.

On the TV monitor, her boyfriend, Jimmy Kimmel, whose late night talk show is taped at the El Capitan, is interviewing Val Kilmer. Silverman loves Kimmel, and loves to talk about how much she loves Kimmel, but right now, she's intrigued by Kilmer, who looks a little puffy onscreen.

"He looks so ... like if you soaked Val Kilmer in water," she says with a quizzical look on her face.

Innocent and apt, unexpected and delivered in a tone of wonder, the tossed-off line is a mild version of Silverman's comedic stock in trade, which will be on full-throated display a couple of hours later during an 18-minute set at The Improv, a few miles away.

There, for a full house, she will roll around on top of a grand piano and punctuate some of her older bits with new material: "I was at a red light and I thought there was an earthquake and my heart was pounding and I realized it was the bass coming from the big Suburban behind me," she will say. "And it made me realize that in years to come, there's going to be a whole generation of elderly deaf black people. ... And I do not mean this in a racist way. It tickles me a little bit." Most people laugh, a few groan. But as Silverman is fond of saying, and will repeat later, on stage: "I don't care if you think I'm racist. I just want you to think I'm thin."

COMEDY CENTRAL PILOT

After many years of steady work and moderate success, including a traumatizing stint at 22 as a writer and performer for "Saturday Night Live," Silverman appears to be on the brink of something bigger. She has a standout appearance in the dirty-joke documentary "The Aristocrats." A movie based on her off-Broadway show, "Jesus Is Magic," directed by Liam Lynch, had its Los Angeles premiere yesterday. She has just finished shooting a pilot for her own Comedy Central show. And yet, something about all these projects feels disquietingly familiar to Silverman.

"I mean, it's been, 'This is gonna be your year' for about 10 years in a row," she says, sitting at the long wooden writers' table outside Kimmel's office after his taping ends. "Who knows what will happen when the movie opens or if the show goes? They both feel like things that might happen or bear fruit. ... I've been at the cusp of this over and over, but this time seems a little more real."

People sometimes recognize Silverman from the hit 2003 Jack Black movie "School of Rock" (she played Black's roommate's snitty girlfriend), the Fox show "Greg the Bunny" or the HBO sketch comedy series "Mr. Show." She played a comedy writer on Garry Shandling's HBO tour de force "The Larry Sanders Show." She was Kramer's girlfriend Emily on a couple of "Seinfeld" episodes in 1997. On Comedy Central's "Crank Yankers" — which features puppets acting out crank phone calls — she plays the voice of Hadassah Guberman, who, in one episode, calls a hot-tub store to announce that she was impregnated during a soak in one of their tubs and demands the store pay child support.

"I've been able to stay famous in a way where people, when they recognize me, think they are the only one that does," Silverman says. "I told Jimmy, 'In the next few months, I might get really famous, and I hope you can handle it.' He says he can." She lowers her voice conspiratorially and twists her elastic mouth sideways, the way she sometimes does for a punch line. "That remains to be seen."

Kimmel strolls over to say goodbye. Silverman, who often jokes onstage about Kimmel's less-than-impressive physical gifts, lights up. "Isn't he distracting?" she asks. "He's very personable."

So, he is asked, is his girlfriend of three years as loving and supportive in private as she acts? Is Sarah's mooning for real?

Kimmel smiles. "When you say 'mooning,' do you mean does she pull her pants down and hang it out the window? She is all those things. I am not as good, but I try. I feel it, but I won't say it."

After Kimmel leaves, Silverman says marriage is not in the cards. "I don't want to belong to some kind of cult that doesn't include everybody. That disgusts me. That gay people can't get married is just so absurd. I don't want to be part of it. Plus, I just like being lovaaaahs."

Sure, she says, with a perfectly straight face, she and Kimmel, who is Catholic, have their differences: "He believes the Holocaust didn't happen. And I say it did. But you have to put these things aside for love." She's joking, but with Silverman, as with most comics, the line between "on" and "not on" is a thin one.

NO DEPRESSION JOKES

Silverman, who was raised in a liberal New Hampshire household, is Jewish. One of her three sisters is a "super-duper reform" rabbi, and is the mother of four children — three biological daughters and an adopted son from Ethiopia. (She and her husband are about to adopt a second Ethiopian child.) Nevertheless, Silverman jokes about the Holocaust ("My grandmother was in one of the better camps.") and starving African babies ("I see these CARE commercials with these little kids with the giant bellies and the flies and these are 1- and 2 -year-old babies ... nine months pregnant! And it breaks my heart in two.")

In keeping with her tomboyish demeanor, she considers herself a "fun uncle" to Kimmel's children, 12-year-old Kevin and 14-year-old Katie, who hang out with their divorced dad in a room off his office that is outfitted with computers and bunk beds.

And though she adores kids, Silverman says, she does not want any. "Maybe down the line, in my 40s, I might want to adopt, but for a few reasons I just do not care to have biological children," she says. "I feel like, other than vanity or ego, I can't justify it. There's just millions of kids that have no parents, and it seems crazy just because you want to see a little you to have a baby. And I also think that everyone has things about themselves that they don't like, and I am afraid to see that. ... My parents, my sisters and I, all of us had a lot of sadness in our childhoods; it's in our genes. Depression. And I just can't bear to see it. ... "

She says she avoids only one subject in her comedy. "Fat jokes about women bum me out. I never find them funny. That said? There always could be a fat joke about a woman that is so funny it's great." But she does not joke about depression, either.

Occasionally, critics compare her to Lenny Bruce, whose vicious satire and foul language changed stand-up forever. But Silverman claims to have no greater purpose than getting a laugh. "I feel a little bit like Peter Sellers in 'Being There,' " she says, referring to the character Chauncey Gardiner, whose simplistic utterances were taken as proof of a great intellect. "I'm just going for laughs, and if people have found depth in it, I am not trying to debate that, but it's not premeditated."