To prepare for monitoring the health, social and economic impacts of this policy change, a greater understanding of the long-term trends in the prevalence of cannabis use in Canada is needed. [...] Analysis of comparable data from the Canadian Tobacco Use Monitoring Survey and the Canadian Tobacco, Alcohol and Drugs Survey for the 2004-to-2015 period suggests that use was stable among 15- to 17-year-old males, decreased among 15- to 17-year-old females and among 18- to 24-year-olds (both sexes), and increased among people aged 25 or older. [...] Given the complexity of the For much of the period it was not Limitations subject, the dynamism of drug use possible to separate medical from behaviour, and consequences of con- non-medical use and therefore the results This study has a number of strengths sumption,6,10,45-50 the availability of do not distinguish between the two. [...] Prevalence of marijuana use disorders in Addiction Survey (CAS): A National Survey Trends in use of marijuana and attitudes the United States between 2001-2002 and of Canadians’ Use of Alcohol and Other toward marijuana among youth before and 2012-2013.