The onset of marijuana use from preadolescence and early adolescence to young adulthood

Although it is well documented that intrapersonal and interpersonal risk fa ctors are related to the frequency of marijuana use, much less is known abo ut the initiation of marijuana use. This paper reports on a longitudinal st udy of the personality, family, peer, and ecological predictors of marijuan a onset. Survival analysis was applied to a sample of nonusers of illegal d rugs, followed from age 9 years to the 20s. The major findings indicate tha t (a) youngsters who are unconventional are at a higher risk for marijuana initiation; (b) youngsters who associate with peers who use marijuana or wh o smoke tobacco themselves are at increased risk for marijuana initiation: (c) youngsters who identify with their parents are less likely to begin mar ijuana use: and (d) the predictors related to marijuana onset emerged durin g preadolescence, early adolescence, middle adolescence, late adolescence, and the 20s. Results are discussed within the framework of a family interac tional perspective of development. Implications for prevention are discusse d.