This study focuses on a particular model for the supply of cannabis: Cannabis Social Clubs (CSCs). CSCs are an intermediate, non-profit model, which rely on in-house growers to cultivate the cannabis that is distributed among CSCs’ adult members. CSCs have first emerged in Spain, but can be found in many other European countries today, although little is known about their features and the ties among them. Drawing on a mixed methods design, this study contributes to filling that research gap by providing a mapping of the CSC presence across the European Union member states. The development of collaborative relationships among CSCs across countries will be explored, as well as the transfer of knowledge and/or practices, and eventual emergence of a transnational movement. As such, this study draws on social movement literature, particularly with regards to transnational processes. Special attention will be given to how European CSCs have operationalized the key principles and design characteristics typically associated with this model. As CSCs have primarily been driven by the (self-regulatory) efforts of cannabis users and activists, it is likely that practices may differ across settings. In order to gather in-depth insights on a relevant but under-researched CSC-setting, additional fieldwork will be carried in the UK. This study is relevant to develop the thinking on ‘supply architectures’ and its design, and is informative for current discussions about cannabis legalization.