Background: Chemicals with endocrine-disrupting abilities may act as obesogens and interfere with the body's natural weight-control mechanisms, especially if exposure occurs during prenatal life. Objective: We examined the association between prenatal exposure to polychlorinated biphenyls (PCBs) and p,p′ -dichlorodiphenyldichloroethylene (DDE) and subsequent obesity at 5 and 7 y of age. Design: From 1997 to 2000, 656 pregnant Faroese women were recruited. PCB and DDE were measured in maternal serum and breast milk, and children's weight, height, and waist circumference (WC) were measured at clinical examinations at 5 and 7 y of age. The change in body mass index (BMI) from 5 to 7 y of age was calculated. Analyses were performed by using multiple linear regression models for girls and boys separately, taking into account maternal prepregnancy BMI. Results: For 7-y-old girls who had overweight mothers, PCB was associated with increased BMI (β = 2.07, P = 0.007), and PCB and DDE were associated with an increased change in BMI from 5 to 7 y of age (PCB: β = 1.23, P = 0.003; DDE: β = 1.11, P = 0.008). No association was observed with BMI in girls with normal-weight mothers. PCB was associated with increased WC in girls with overweight mothers (β = 2.48, P = 0.001) and normal-weight mothers (β = 1.25, P = 0.04); DDE was associated with increased WC only in girls with overweight mothers (β = 2.21, P = 0.002). No associations were observed between PCB or DDE and BMI in 5-y-old girls. For boys, no associations were observed. Conclusions: Results suggest that prenatal exposure to PCB and DDE may play a role for subsequent obesity development. Girls whose mothers have a high prepregnancy BMI seem most affected.