LAUSR

OBJECTIVE Prior research among adolescents has identified injunctive and descriptive norms as predictors of marijuana use. Yet, there is no consensus on which norm (i.e., injunctive or descriptive) or referent group (e.g., parents, peers, closest friend) is most consistently related to adolescent marijuana use. The objective of this review is to synthesize literature on perceived social norms and adolescent marijuana use and to identify the referents most commonly studied in relation to adolescent marijuana use. METHOD A systematic review, following PRISMA guidelines, assessed studies published from 1998 to 2018 that reported the impact of adolescents' perceived injunctive norms and descriptive norms on self-reported marijuana use. Seventeen peer-reviewed English-language studies met inclusion criteria. RESULTS Across cross-sectional and longitudinal studies, injunctive norms and descriptive norms significantly predicted adolescent marijuana use. Peer norms were the most commonly measured descriptive norm and were found to be most positively related to marijuana use. Parental norms were the most measured injunctive norm and were also positively related to use. CONCLUSIONS Injunctive norms and descriptive norms are key factors in considering adolescent marijuana use, although peer descriptive norms may be most influential. The lack of systematic definition and measurement of marijuana use, norms, and referents was apparent in the literature. Future research should systemize norm constructs and explore differences in the norm-marijuana use relationship among adolescents with intersecting identities (e.g., gender, race) and social network referents (e.g., family, peer groups).