A review from the Movie Snob:

thirteen. (B) This is a gritty independent flick about a thirteen-year-old girl's rapid descent from wholesome innocence into a lifestyle of larceny, alcohol, drugs, and promiscuity. The immediate catalyst for her transformation is her new friend Evie, a bad girl whose badness makes her one of the most popular girls in school. But the film strongly suggests that background factors are at work as well--the protagonist lives with her divorced mother (played by Holly Hunter) who is in AA, has a no-good boyfriend, and can barely keep her act together. The protagonist's father seems well-meaning but has problems of his own that keep him away most of the time. A few critics have dismissed this movie as an overwrought TV movie-of-the-week, but I thought it was well done. Remarkably, the actress who plays Evie co-wrote the screenplay, apparently drawing on some personal experiences.