This study examined the temporal associations of cigarette smoking with prosmoking social influences, academic performance, and delinquency in a cohort of 6,527 adolescents surveyed at ages 13, 16, 18, and 23 years. Prosmoking peer and family influences were risk factors for future smoking throughout adolescence, with family influences perhaps also operating indirectly through the adolescent's exposure to prosmoking peers. There were reciprocal associations of youth smoking with parental approval, peer smoking, and poor grades (but not delinquency), with youth smoking emerging as a stronger antecedent than consequence of these psychosocial factors. Few gender differences in these associations were observed. Implications of these findings for efforts to prevent youth smoking are discussed.