Abstract
Cannabis use has become common, but we still understand little about how and why people use cannabis. This paper theorises the relationship between cannabis use and social identity, suggesting that cannabis use is an important aspect of many people's identities, and that the reasons for, or meaning, of cannabis use change and vary, over time and by situation. If cannabis use is important to people's identities, then this needs to be understood in the context of a dynamic theory of social identity. Also, issues related to social identity need to be properly understood if we are to formulate rational social policies dealing with cannabis use.