This study investigates the role of several social psychological variables which could help explain the process by which Puerto Rican adolescents become vulnerable to drug use involvement with exposure to a host society, New York City, where the prevalence of drug use is higher than in the society of origin, Puerto Rico. To study how acculturation affects the psychosocial factors associated with adolescent drug use, four generational status groups of Puerto Rican students living in two settings—New York City and San Juan, Puerto Rico—were surveyed: New York Ricans (New York City-born Puerto Ricans); New York migrants (island-born Puerto Ricans living in New York); Puerto Rican islanders (adolescents who had never lived outside of Puerto Rico); and Puerto Rican immigrants (New York City-born youngsters of Puerto Rican parentage whose families had returned to live on the Island). A theoretical model developed to explain adolescent problem behavior, which posits a continuum of antecedent, intrapersonal, interpersonal and perceived environment dimensions theoretically conductive to adolescent drug use, guided the analysis. Analysis of variance was used to test for generational status group differences in each of the psychosocial risk factors. The relationship between generational status, the intervening psychosocial variables, and drug use were explored through multiple regression analyses. The data showed that Puerto Rican youth's generational status was systematically related to differences in the occurrences of the social psychological risk factors for adolescent drug use involvement. With greater exposure to the New York City environment, Puerto Rican youngsters were more likely to report problems in parental socialization, personal control and perceived environment domains. Each of the psychosocial characteristics was associated with the students' drug use involvement, and these relationships were conditioned by generational status. New York Ricans exhibited the greatest susceptibility to drug use involvement in the presence of weakening of parental controls, increased tolerance of deviance and drug use, increased unconventionality with respect to school and church, and peer use of legal and illegal drugs. Sociodemographic and psychosocial variables together explained 47% of the variance in the drug use involvement of Puerto Rican adolescents.