Using group‐based trajectory modeling, this study examined 5156 adolescents from the child sample of the 1979 National Longitudinal Survey of Youth to identify developmental trajectories of obesity from ages 6–18 and evaluate associations of such trajectories with risk behaviors and psychosocial health in adolescence. Four distinctive obesity trajectories were identified: “Chronically Obese,” “Decreasing,” “Increasing,” and “Non‐obese.” Males were overrepresented in the Chronically Obese and Increasing groups; females were overrepresented in the Decreasing group. African‐Americans were overrepresented in the Chronically Obese, Increasing, and Decreasing groups; in contrast, Whites were overrepresented in the Non‐obese group. Obesity trajectories were not associated with greater trends in alcohol use, marijuana use, or delinquency, but Chronically Obese adolescents showed a greater increase in cigarette smoking over time compared to other trajectories. The Increasing trajectory, representing a transition into obesity status from childhood to adolescence, was associated with poorer psychosocial health compared to other trajectories.

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