OBJECTIVE:To assess the relationships between mothers' reports of dieting and encouraging adolescents to diet and adolescents' reports of their own dieting practices and weight-related concerns. DESIGN: Cross-sectional study of parent interviews and adolescent surveys in an ethnically-diverse sample. SUBJECTS: A total of 810 adolescents (n ¼ 381 boys and n ¼ 429 girls) and their mothers. RESULTS: Mothers' dieting was associated with their adolescent girls' weight-related concerns and behaviors, but these associations were not significant after adjusting for girls' body mass index (BMI). In contrast, mothers' encouragement for sons to diet was associated with sons' binge eating, dieting and other weight-control behaviors, even after controlling for sons' BMI. Compared with mothers who did not encourage their child to diet, mothers who encouraged their child to diet were significantly heavier women and were more likely to view their child as overweight. Forty-three percent of boys and 46% of girls who were encouraged by their mothers to diet were classified as nonoverweight by federal guidelines. CONCLUSIONS: Boys who are encouraged by their mothers to diet may be at risk for health-compromising eating and dieting behaviors, particularly binge-eating, fasting, eating a little bit of food and skipping meals. Parents who are concerned about their children's weight should be educated to encourage healthy eating habits and physical activity to promote their children's health, including healthy weight control.