Montano, Ashley NicoleAmong researchers, there has been a long-standing debate on the issue of whether alcohol and marijuana are used as substitutes or complements of one another. In other words, does the increased usage of one decrease the usage of the other (substitution) or does usage of both substances simultaneously increase (complements)? The primary purpose of this study is to identify whether a suggested substitution or complementary effect exists among adolescent drinking patterns following the recent emergences of increased marijuana legalization. To explore these effects, data is used from 38 different states included in the Youth Risk Behavior Surveillance System between the years 1995 and 2017. The primary analysis finds limited support for a substitution effect and no evidence of a complementary effect among adolescents. This study also includes a supplementary analysis providing implications for the direction of future research on the apparent relationship between alcohol and marijuana usage patterns.enThesisCriminologyPublic healthPublic policyadolescentsalcoholcomplementsmarijuanasubstance usesubstitutes