Sociocultural factors that underpin gender differences in body dissatisfaction have not frequently been explored. We examined the relative contribution of internalization of media body ideals and perceived pressure to achieve this ideal in explaining body dissatisfaction in adolescent boys and girls. A sample of 819 boys and 791 girls completed measures of internalization of body ideals, perceived pressure, body mass index (BMI) and body dissatisfaction. As expected, girls showed higher body dissatisfaction, internalization and pressure than boys. Internalization, pressure and BMI contributed to the prediction of body dissatisfaction in boys and in girls although these variables explained less variance in body dissatisfaction in boys. In addition, for girls the strongest predictor of body dissatisfaction was internalization, whilst for boys the strongest predictor was pressure. Differences in extent of internalization and pressure may contribute to higher body dissatisfaction in girls than boys. These sociocultural factors may affect girls and boys differently.