Several jurisdictions are currently considering reforming their cannabis laws with regards to the production and distribution of that substance, and there have been noteworthy policy changes in this area in recent years, especially in the Americas. One of the central arguments (and goals) associated with the legalization of a non-medical cannabis market is the reduction or elimination of the illicit market. Nevertheless, we know very little about whether and how the introduction of a legal cannabis market may affect the illicit market and its players. The proposed study seeks precisely to shed light onto the eventual supply-side changes following cannabis legalization. In particular, the focus falls on understanding: 1) how pre-existing illicit cannabis suppliers have adapted to a post-cannabis-legalization context; and 2) the extent to which new non-official supply actors have emerged in that context. To achieve these research goals, the study draws on Uruguay as a case study. The research design envisions the collection of multiple data sources, including secondary data (e.g. official statistics, policy reports and other documentary sources), court files, and interviews with three groups of participants: representatives of law enforcement, of the national cannabis agency, and with imprisoned illicit cannabis suppliers in Uruguay. It will be one of the first studies to explore eventual adaptations of illicit cannabis suppliers in a post-legalization framework.