Cannabis is the most commonly used illicit drug in the Western world.1 Despite the extent of its use, the eects of cannabis use and dependence on health and psycho-social functioning are often under-recognised. This represents missed opportunities for health promotion and early interventions for young people who may already be experiencing cannabis use-related diculties.Overall, use of cannabis presents a mixed picture, with use stabilising in some countries, yet reducing or increasing in others. Also evident, is that gender differences appear to be diminishing among young people who use cannabis, and Indigenous communities in the US, Australia and some Paciﬁc Islands appear to have higher levels of cannabis use than the non-Indigenous populations.2In addition, there is debate regarding the regulation or decriminalisation of cannabis. High proﬁle sports people, entertainers and even politicians have made their views and histories of cannabis use known, or have been exposed by mainstream or web-based social media. Young people are aware of this, and despite exposure to confusing messages, are expected to make informed choices. Also relevant is past and present use of cannabis by some parents, older siblings and even teachers, reinforcing a view that cannabis is a ‘soft drug’ with minimal consequences for physical and mental health. Such views ignore signiﬁcant changes in the patterns of cannabis use over the past 40 years, which include a decline in the age of initiation of use, an increase in use of more potent cannabis, and more frequent and heavier use by young people — with peers and whenalone.