The impact of heavy cannabis use on young people Vulnerability and youth transitions Margaret Melrose with Penny Turner, John Pitts and David Barrett This study explores young people’s views of what constitutes ‘heavy’ cannabis use and how their usage affects their lives. Surveys tell us that a fairly large proportion of young people have tried cannabis. But we know relatively little about which young people are regular or ‘heavy’ users, what constitutes ‘heavy’ use, or what sorts of cannabis this involves. We also know very little about the personal and social effects heavy cannabis use may have or how young people view such use. For this study, researchers interviewed 100 16- to 25-year-olds who are or have been regular cannabis users, and 30 professionals working with them in various contexts. The report explores: what sort of cannabis these young people used and how they used it their definitions of what constitutes ‘heavy’ use and how these vary between individuals when, why and how they began to use cannabis and why they continue to do so participants’ accounts of the positive and negative impacts of regular cannabis use anomalies and complexities in participants’ attitudes towards cannabis. Through the follow-up interviews the report also examines any links between changes in cannabis use and participants’ social situations over time. The researchers draw on their findings to make recommendations for the development of policy and practice in this field.