The role of peer influence in shaping developmental trajectories of substance use expectancies in early adolescence.

OBJECTIVE: Substance use expectancies are beliefs about the anticipated effects of substance use, serving as key developmental precursors to adolescent substance use. However, the longitudinal trajectories of these expectancies, both substance-specific and higher order cognitive schemas, remain understudied. This study examined the developmental patterns of positive and negative substance use expectancies about alcohol, marijuana, and nicotine use as well as the time-varying influence of deviant peer affiliation and peer intolerance of substance use as environmental correlates of expectancies. METHOD: = 11,499; ages 9-13 years). Parallel process and second-order latent growth curve modeling were used to examine trajectories of substance-specific and higher order schemas for expectancies during early adolescence. RESULTS: Positive substance use expectancies increased across all substance types. Negative expectancies showed distinct developmental patterns by substance: increasing for alcohol, decreasing for marijuana, and remaining stable for nicotine. Deviant peer affiliation was associated with increased positive expectancies, whereas peer intolerance of substance use predicted lower positive and higher negative expectancies across time. CONCLUSIONS: These findings highlight the dynamic development of substance use expectancies in adolescence and support peer influence as a critical factor shaping cognitive vulnerability to future substance use. (PsycInfo Database Record (c) 2026 APA, all rights reserved).