"The story has a large autobiographical aspect," the hyper writer-director says of the 1976-set comedy of a 16-year-old girl's sexual awakening that incorporates a gold mine of insecurity, neurosis and class conflict. "What we discovered is that even though the streets were lined with gold, we still didn't have any. The whole context of growing up on the outskirts of Beverly Hills in a motherless household, that's my own history. I always wanted to mine the period in which I grew up there as the first movie I made."

Jenkins, a former performance artist in New York, moved on to make short films at NYU's graduate program, and made her mark when they were shown at Sundance. Her background may be what emboldened her to make the tonal shifts from comedy to drama in the often appallingly detailed nightmare of Vivian's nomadic adolescence. There are laugh-out-loud scenes, but Jenkins has made a tragedy in sheepish clothing. She expresses at least mild concern about how the film will be perceived. "The whole need to categorize things as comedy or drama, it happens without it necessarily being your intention. Nothing that's a hybrid is properly perceived in the world of marketing, although that's the kinds of thing that I like."

The casting of the movie is particularly adept, a roster of memorably fidgety performers. As Vivian, Natasha Lyonne is a voluble presence, a wisenheimer diva with the amused-by-life smile of either a preternaturally wise person or a lunatic. Alan Arkin is as mesmerizingly intense as ever as her divorced father, along with pot-addicted overachieving teenage brother (David Krumholtz) and a cranky little brother (Eli Marienthal). Then there's Marisa Tomei as Rita, a cousin just escaped from drug rehab. Jenkins says she was casting for dramatic chops more than comedic ones. "Sometimes you're talking to an actor who says, 'It's supposed to be funny, right?' and you go, yeah, but you don't know you're in a scene. You're just experiencing life.

The characters in this film are not walking around saying, 'Hey, we're in a comedy so we have to act like we're in a comedy.' Too many movies, actors seem to be doing that."

Natasha Lyonne, hair piled high, face filled with fleeting expressions and instants of adolescent terror, is simply remarkable. But, Jenkins says, "When her name was mentioned to me when I was looking all over the place for an actress to play Vivian, I said, oh no, she is totally wrong, based on 'Everyone Says I Love You.' Her performance was really mannered in that movie. Then I met her and her actual human-beingness, I was very interested." Lyonne was game. "She was sick of playing daughters. She's at an age she wants to be a grown-up already. She was 18 when we made the movie, and I told her, look at [Truffaut's] '400 Blows' and she became really excited at the power of following someone at a young age which she had discredited as dumb girl stuff. I wanted an adolescent survival story less than a story about mortification." Jenkins says she was following her muse more than any other filmic influence. "There weren't any movies whose tone I was borrowing from. I love Billy Wilder, who plays with tone, movies like 'The Apartment.' A combination of dark and light like that would be something I would aspire to."

Several times in the story, the Abramowitzes move from one apartment to another in the middle of the night. "These tacky apartment houses in Beverly Hills have all these names like 'The Paradise' and 'The Capri' that promise this life of leisure. But they're like California tenements, but with this fake fanciness. Living on the edge of wealth gives you a kind of inferiority complex, which is true of the whole family, especially her father. But I was interested in how much that mirrored the inferiority a 15-year-old girl like Vivian already felt."

The offhandedness of Jenkins' depiction of Vivian's tribulations makes them even more pungent. When her racy cousin Rita joins the clan, Vivian has an older female figure to learn from, even if a slightly deranged and truly loose one. One scene between them is particularly rich, a gleeful dance they share to "We Got The Bump" where Rita and Vivian are tossing a vibrator around; gee, wouldn't it be awful if dad walked in on that? "There was no privacy. Female coming of sexual age is very public, particularly if you have breasts and there is something the world can scrutinize. The world starts treating you differently while you're straddling girlhood and adulthood. You don't have the manual for dealing with it, yet you're walking around with all this hardware."