Eligible adolescents and emerging adults (ages 12-25) who have used cannabis in the past year will attend 1-2 laboratory visits. They will complete a series of interviews and self-report measures, including assessment of cannabis quantity and frequency, subjective effects of cannabis, and problems due to cannabis use. They will provide a urine sample for analysis of a THC metabolite and they will provide a blood sample for analysis of genes related to cytochrome P450 enzyme activity, which are thought to be associated with metabolism of THC.

Adolescents who regularly use cannabis will record their cannabis use in real-time via a mobile app for two weeks. Participants will be asked to report the method (i.e., joints, blunts, dabs), estimated quantity, and estimated potency of their recent cannabis use. In addition to monitoring cannabis use in real-time, participants will complete other assessments on the mobile app five times per day. Participants will attend three in-person office visits (remote participation is also possible).