LAUSR

OBJECTIVE Simultaneous alcohol and marijuana (SAM) use is associated with heavier alcohol and marijuana use and more negative consequences, but less is known about the social, physical, and temporal contexts of SAM use. METHOD Young adults (N=409, 51.2% female, 49.1% White Non-Hispanic) who reported past-month SAM use completed up to 14 daily surveys across five bursts that assessed SAM use and negative consequences and social, physical, and temporal contexts. We used multilevel models to examine SAM use context' associations with alcohol/marijuana quantity and consequences. RESULTS The social context of alone only (versus with others only) was associated with consuming fewer drinks. Physical contexts that included using both at home and outside the home (versus only at home) were associated with greater alcohol and marijuana quantity and negative consequences (but not after controlling for alcohol quantity); use outside the home only (versus only at home) was associated with more alcohol use, more alcohol consequences (but not after controlling for alcohol quantity), and fewer marijuana consequences (even after controlling for marijuana quantity). The temporal context of first engaging in SAM use before 6PM (versus after 9PM) was associated with greater alcohol and marijuana quantity and more marijuana consequences (but not after controlling for number of hours high), and first engaging in SAM use between 6-9PM was associated with more hours high. CONCLUSIONS SAM use contexts such as using with others, outside the home, and earlier in the evening are typically associated with greater alcohol/marijuana quantity and consequences.