Background: Low physical fitness, obesity, and the combination of the two in adolescence may be related to risk for disability in adulthood, but this has rarely been studied. Objective: To examine individual and combined associations of cardiorespiratory fitness and obesity in male adolescents with later receipt of a disability pension due to all and specific causes. Design: Population-based cohort study. Setting: Sweden. Participants: 1 079 128 Swedish adolescents aged 16 to 19 years who were conscripted into the military between 1972 and 1994. Measurements: Cardiorespiratory fitness and body mass index (BMI) were measured at conscription and were related to information on later receipt of a disability pension obtained from the Social Insurance Agency. Results: Over a median follow-up of 28.3 years, 54 304 men were granted a disability pension. Low cardiorespiratory fitness was strongly associated with later receipt of a disability pension due to all causes (hazard ratio, 3.74 [95% CI, 3.55 to 3.95] for lowest vs. highest fitness decile) and specific causes (psychiatric, musculoskeletal, injuries, nervous system, circulatory, and tumors). Obesity was associated with greater risk for receipt of a disability pension due to all and specific causes, with the greatest risks observed for class II and III obesity. Compared with being unfit, being moderately or highly fit was associated with attenuated risk for receipt of a disability pension across BMI categories. Limitation: The cohort did not include women, had data on smoking and alcohol intake only in a subsample, and lacked repeated measures of exposures and covariates. Conclusion: Low cardiorespiratory fitness, obesity, and the combination of the two were strongly associated with later chronic disability due to a wide range of diseases and causes. Although additional well-designed studies are required, these findings support the importance of high cardiorespiratory fitness and healthy body weight during adolescence to prevent later chronic disease.