THE CONSISTENCY OF FAMILY AND PEER INFLUENCES ON THE DEVELOPMENT OF SUBSTANCE USE IN ADOLESCENCE

Latent growth modeling (LGM) was wed to analyse longitudinal data for adolescent substance use from Jive overlapping age cohorts (11, 12, 13 , 14 and 15 years at first assessment) measured at four annual time po ints. An associative cohort-sequential model was tested for alcohol, c igarette and marijuana use with a sample of 345 adolescents (11-18 yea rs old) from an urban area in the Pacific Northwestern region of the U nited States. Hypotheses concerning the shape of the growth curve, the extent of individual differences in the common trajectory over time, and the influence of family cohesion, peer encouragement and gender on initial substance use and shape of the growth curve were tested Resul ts indicated similarities between alcohol, cigarette and marijuana ini tial use and development, with peer encouragement and family cohesion predictive of initial levels of we, and changes in peer encouragement influencing the developmental trajectories of the three substances. Fe males were higher than males in initial status and developed less rapi dly in their use of the substances than did males. Findings are discus sed in terms of the similarities and differences in the developmental trajectories of the three substances and the importance of family and peer influences on these trends.