Patients seeking services or currently engaged in care at an existing comprehensive outpatient program for adolescents and young adults with substance use disorders (the MGH Addiction Recovery Management Service) are eligible for this study. Participants will be randomized to receive either UP + TAU or TAU alone. The adjunctive UP intervention consists of 16 twice-weekly group sessions (delivered over an 8-week period) designed to deliver transdiagnostic, emotion-focused CBT strategies.