To assess the prevalence rates and correlates of overweight, concern with weight, and bulimic behaviors. A survey was completed by a population-based sample of 16,114 boys and girls aged 9 to 14 years. Although fewer girls (19%) than boys (26%) were overweight, more girls (25% versus 22%) perceived themselves as overweight (p < .001). The proportion of girls reporting trying to lose weight increased with age (p < .001). The prevalence of binge eating at least monthly increased with age among the girls, but remained stable among the boys. The prevalence of purging was low (< or = 1%) and comparable between genders until age 13. Among the 13- and 14-year-olds, girls were significantly more likely than boys to report using laxatives or vomiting to control weight (p < or = .001). Purging was independently positively associated with stage of pubertal development (girls: odds ratio [OR] = 2.1, 95% confidence interval [CI] 1.6-2.7; boys: OR = 1.5, 95% CI 1.0-2.2) and overweight (girls: OR = 1.9, 95% CI 1.2-3.0; boys: OR = 2.7, 95% CI 1.4-5.1). Misperception of being overweight and concern with weight were common. Purging was a very rare behavior, but increased with pubertal development. Among the girls, the prevalence increased sharply around the onset of adolescence.