The probable nadir of Riding In Cars With Boys—a fairly free adaptation of Beverly Donofrio's memoir of growing up in 1960s Connecticut as a teenage mother with aspirations of becoming a writer—comes at about the halfway point. Deep in the grips of heroin withdrawal, husband Steve Zahn tries desperately, and without success, to vomit in a wastebasket rather than on the bed, as Drew Barrymore, playing Donofrio, looks on. Her response: "This is so gross." True, the movie is largely about how Barrymore's youth makes her ill-equipped to handle marriage and motherhood, but the mallrat inflection of her delivery only points to how ill-equipped she is for the role. As the film jumps across time, Barrymore plays Donofrio both as a 15-year-old (accomplished by keeping her eyes wide) and a woman in her mid-30s (accomplished by keeping her lips pursed). In either setting, no amount of makeup can keep her from looking comically out of place, particularly in the latter setting, when Adam Garcia, an actor two years her senior, plays her son. It could be argued that such details are ultimately superficial. Judy Garland looks nothing like a little girl in The Wizard Of Oz, and James Caan looks nothing like Al Pacino's brother in The Godfather. But Riding In Cars With Boys never looks like anything more than a filmed game of dress-up, which creates an 800-pound gorilla of a problem—and there's not much of a movie hiding behind the ape. Appearances aside, Barrymore's performance relies on vocal mannerisms seemingly borrowed from director Penny Marshall. Marshall's direction, meanwhile, appears to take inspiration from teenage diary entries, letting the tone vary from comedy to melodrama with the regularity of an adolescent mood swing, and keeping the film focused squarely on Barrymore. As a result, Barrymore's relationships with her son (played as a child by a succession of young actors), mom Lorraine Bracco, policeman dad James Woods, husband Zahn, and best friend Brittany Murphy slip into the background, awkward and underdeveloped, as Barrymore's personal goals meet with one setback after another. Even the production design suffers from the neglect: It trots out uniform styles of hair and clothing, just as the soundtrack serves up one overplayed, era-signaling hit after another (from "I Feel Good" to "Rebel Yell"). In the end, Riding In Cars With Boys is interesting only as an example of how one person's life can look like another's vanity project.