Cannabis use is prevalent among adolescents, and heavy use often leads to cannabis use disorder (CUD) in this population. Further, changes in legislation coupled with the increasing availability of high-potency cannabis products and evolving routes of administration may confer greater risks of use for this uniquely vulnerable group. In this chapter, we review several important areas relevant to the study of heavy cannabis use and CUD including prevalence, diagnostic criteria, screening, health and mental health comorbidity, psychosocial functioning, and behavioral and pharmacological treatments. CUD is associated with negative mental and physical health, neurocognitive, and multiple domains of psychosocial outcomes, although causality is difficult to demonstrate. Evidence-based behavioral therapies, largely consisting of cognitive, motivational, behavioral and family-based approaches remain the treatment of choice for adolescent CUD. There is limited evidence for pharmacological treatments at this time. Future work may further expand our understanding of the implications of CUD among youth by exploring the impact of increasing legalization, availability of more potent cannabis products, and the development and testing of novel behavioral and medication interventions to treat CUD.