RecruitingBehavioural interventionAdverse Adolescent Pathways to Substance UsePurpose: This 5-year R01 study will elucidate the role of maturational change across adolescence in neural connectivity and physiological stress responses in the relationship between anxiety and adverse pathways to substance use (APSU). Participants: Children (N=200) aged 12-14 with symptoms of anxiety and their legal caregiver will be recruited from clinical and community sources. Procedures: Youth participants will complete several questionnaires and interviews, undergo neuroimaging while performing cognitive tasks, and have their heart rate and skin conductance monitored during a mildly stressful task. Caregivers will complete several questionnaires.