Recent research suggests that overweight females suffer penalties in the labor and marriage markets, while overweight males do not. This study explores whether similar gender differences in the effect of body weight exist in what Cawley et al. (2006) labeled ‘the adolescent sex market’. Drawing on data from the National Longitudinal Study of Adolescent Health, we use fixed effects and instrumental variables identification strategies to estimate the relationship between body weight and sexual activity. We find evidence that increased body weight lowers the probability that female adolescents become sexually active. In contrast, there is little evidence of a causal relationship between body weight and sexual activity for male adolescents