In a sample of 1897 youth studied across the last year of elementary school to the second year of high school, we (a) characterized different developmental trajectories of drinking frequency and drinking-related problems and (b) tested an a priori risk model that predicted variation in trajectory group membership. Analyses revealed five separate trajectories for both drinking frequency and drinking problems. Wave 1 scores on impulsigenic traits, expectancies for the reinforcing and stimulating effects of alcohol, and early pubertal onset differentiated among the trajectory groups, in some cases before the groups differed in drinking behavior. We also found substantial covariation between membership in high drinking frequency groups and membership in groups experiencing problems from alcohol consumption. The findings suggest that (a) youth vary considerably in the development of drinking behavior, and (b) trajectory groups can be distinguished by specific biological, personality, and learning risk factors
