OBJECTIVE: To establish (1) if obesity in adolescence predicts a long history of unemployment and other adverse social outcomes at age 31 y and, conversely, (2) the effect of a long history of unemployment on the risk of obesity at 31 y. DESIGN AND SUBJECTS: A longitudinal, population-based study of 9,754 subjects born in 1966 in Northern Finland was conducted. The cohort members were studied at birth, 1, 14 and 31 y. MEASUREMENTS: Body mass index (BMI) at 14 and 31 y; work history, as self-reported at 31 y and as recorded in national registers of the total number of days each subject had received unemployment allowance between 1985 and 1997; place of residence at 14 and 31 y; family social class at 14 y; subject's school performance at 16 y; marital status and number of children at 31 y. RESULTS: Overweight and obesity at 14 y did not predict a long history of unemployment at 31 y, but were associated with a low level of education, and being single or divorced at 31 y among females. A long history of unemployment (register data) was associated with an increased risk of obesity among women, but not men, after controlling for potential confounding factors (social class at 14 y, BMI at 14 y, school performance at 16 y, place of residence, and number of children). The adjusted OR (95% CI) was 1.09 (0.72-1.63) for men, and 1.64 (1.07-2.50) for women. CONCLUSION: Adverse social outcomes of adolescent obesity seemed to emerge more for women. Subjects with low school performance and women with a long unemployment history are at increased risk of obesity.