Marijuana policy is rapidly evolving in the United States and elsewhere, with cannabis sales fully legalized and regulated in some jurisdictions and use of the drug for medicinal purposes permitted in many others. Amidst this political change, patients and families are increasingly asking whether cannabis and its derivatives may have therapeutic utility for a number of conditions, including developmental and behavioral disorders in children and adolescents. This review examines the epidemiology of cannabis use among children and adolescents, including those with developmental and behavioral diagnoses. It then outlines the increasingly well-recognized neurocognitive changes shown to occur in adolescents who use cannabis regularly, highlighting the unique susceptibility of the developing adolescent brain and describing the role of the endocannabinoid system in normal neurodevelopment. The review then discusses some of the proposed uses of cannabis in developmental and behavioral conditions, including attention-deficit hyperactivity disorder and autism spectrum disorder. Throughout, the review outlines gaps in current knowledge and highlights directions for future research, especially in light of a dearth of studies specifically examining neurocognitive and psychiatric outcomes among children and adolescents with developmental and behavioral concerns exposed to cannabis.