Parents play an important role in influencing adolescent health behaviors and parenting practices may be an important pathway through which social disadvantage influences adolescent health behaviors that can persist into adulthood. This analysis uses the National Longitudinal Study of Adolescent Health to examine how parenting practices mediate the association between family socioeconomic disadvantage, measured as low parent education and family welfare/poverty status, and physical activity in adolescence and young adulthood for males and females. Results show that levels of parental control do not differ by family disadvantage. However, disadvantaged parents engage in lower levels of activities and communication with their children compared with nondisadvantaged parents. These behaviors serve to mediate the negative association between disadvantage and physical activity in adolescence, and are associated with physical activity in adulthood. Parenting is an important pathway through which disadvantage influences physical activity in adolescence and the transition to adulthood.