In 2018, the government of Canada legalized cannabis for non-medical use. In addition to safeguarding public health, the main objective was to divert profits from the illicit market and restricting its availability to youth. This dramatic shift in policy direction introduces new challenges for the criminal justice system due to the persistence of unlawful distribution among persons who refuse to abide by the new law. Continuing unlawful distribution is foreseeable, in part, because of stringent measures to reduce availability by targeting participants in the illegal market. Recognizing that the most heavy, frequent, users account for the majority of cannabis consumed—and are the group most likely to keep purchasing from dealers because of lower costs and easy access—the illegal market will continue to provide a substantial (albeit unknown) proportion of the total volume. The recent change in policy in Canada provides new opportunities for research to assess how legalization of cannabis affects its use and distribution patterns. The National Cannabis Survey (NCS), administered at three-month intervals, allows for multi-wave comparison of prevalence statistics and point of purchase information before and after legalization. Drawing on the NCS, this article examines the extent to which the primary supply source has changed across the provinces, controlling for other factors and consumer characteristics. Findings are interpreted with reference to studies of cannabis law reform in North America informing research and policy observers in these and other jurisdictions, undergoing or considering, similar reforms.