Background and aims: The school-class context is a crucial social environment for young people but substance use researchers have largely overlooked potential influences operating at this level. This study explores associations between school-class and individual-level factors and cannabis use in Swedish youth. Data and methods: Data comprised four waves (2012–2015) of the Swedish Council for Information on Alcohol and Other Drugs’ (CAN) nationally representative school surveys among individuals in 9th and 11th grade. For the present analyses, we had data on totally 28,729 individuals from 2377 unique school classes. Multilevel logistic regressions predicted lifetime and 10+ times use of cannabis from both individual-level predictors and school-class-level measures derived from the individual-level variables. Results: There were individual-level associations between most predictor variables and cannabis use. An early debut of tobacco use and binge drinking as well as low cannabis related risk perceptions had strong associations with cannabis use. Conversely, several school-class-level variables had aggregate relationships with cannabis use, most notably the overall level of risk perceptions in the school class. Some of the school-class factors predicted cannabis use over and above the individual-level covariates, suggesting the presence of contextual effects. Surprisingly, while female gender was negatively related with cannabis use at the individual level, a higher proportion of females in the classroom increased the odds for lifetime cannabis use even after controlling for individual and other contextual-level covariates. Conclusions: Youth cannabis use is related to various factors at both the individual and school-class level in Sweden. Truancy and perceived risk related to cannabis use had contextual associations with cannabis use. The positive contextual association between a higher proportion of females in the classroom and lifetime use should be explored further.

Introduction and AimsResults from previous research are inconsistent regarding the association between socioeconomic status (SES) and cannabis use among adolescents. Since there are risks associated with cannabis use, a social gradient in cannabis use may contribute to reproducing socioeconomic differences in life opportunities. The aim of this study was to assess the association between childhood SES and cannabis use among youth in Sweden.Design and MethodsWe used repeated cross‐sectional data from three waves (2014–2016) of the Swedish national school survey among 11th graders. The analysis encompassed 9497 individuals in 668 school classes. Childhood SES was measured through parents' highest education, as reported by the students. Cannabis use was measured in terms of lifetime use and frequency of use. Data were analysed using multi‐level mixed‐effects Poisson regression.ResultsAdolescents with at least 1 parent with university/college education had 17% (incidence rate ratio 1.17, confidence interval 1.05, 1.30) higher risk of lifetime use of cannabis compared with those whose parents had no university/college education, adjusting for sex, SES of the school environment, academic orientation, truancy, risk assessment and parental permissiveness. Among life‐time users of cannabis, risk for frequent cannabis use was 28% (incidence rate ratio 0.72, confidence interval 0.53, 0.97) lower for those with at least 1 parent with university or college education.Discussion and ConclusionsChildhood SES, in terms of parental education, was associated with cannabis use among Swedish adolescents. Adolescents from families with lower SES were less likely to ever try cannabis, but at higher risk for frequent use.

From 1989 to 2016 there appears to be a positive association between alcohol and cannabis consumption among Swedish adolescents who use cannabis. This association seems to have become weaker over time, suggesting that alcohol and cannabis are neither substitutes nor complements among Swedish adolescents and that the recent decline in youth drinking is not associated with the increase in frequency of cannabis use.