Pressures from the "obesogenic" environment are driving up obesity rates, but adiposity still varies widely within the population. Appetitive characteristics could underlie differences in susceptibility to the environment. We examined associations between adiposity and 2 appetitive traits: satiety responsiveness and food cue responsiveness in children. Parents of 2 groups of children, 8-11-y-olds (n = 10 364) from a population-based twin cohort and 3-5-y-olds (n = 572) from a community sample, completed the Child Eating Behavior Questionnaire. Adiposity was indexed with body mass index (BMI; in kg/m(2)) SD scores. For the 8-11-y-olds, waist circumference was also recorded and used to derive waist SD scores. In both samples, higher BMI SD scores were associated with lower satiety responsiveness (8-11-y-olds: r = -0.22; 3-5-y-olds: r = -0.19; P <0.001) and higher food cue responsiveness (r = 0.18 and 0.18; P <0.001). In the twin sample, waist SD scores were associated with satiety responsiveness (r = -0.23, P < 0.001) and food cue responsiveness (r = 0.20, P < 0.001). By analyzing the data by weight categories, children in higher weight and waist categories had lower satiety responsiveness and higher responsiveness to food cues in both samples (8-11-y-olds: both P < 0.001; 3-5-y-olds: both P < 0.05), but the effect was more strongly linear in the older children. All associations remained significant, controlling for child age and sex and parental education and BMI. Associations between appetite and adiposity are consistent with a behavioral susceptibility model of obesity. Assessing appetite in childhood could help identify higher-risk children while they are still at a healthy weight, enabling targeted interventions to prevent obesity.