 The purpose of the study will be to evaluate the efficacy of a novel integrative therapy that uses cognitive-behavioural approaches to foster the development of these skills in adolescents with ADHD. Adolescents with ADHD, ages 13-17, will be randomly assigned to either 12 sessions of manualized group cognitive behavioural and skills training therapy CBTS or to 12 sessions of manualized supportive group therapy SGT. The CBTS sessions will focus on acquisition of skills targeting the common functional deficits of adolescents with ADHD, with the modules covering psychoeducation, goal attainment, organization, time management, focus training and distractibility reduction, impulse control, study skills, stress management, cognitive restructuring, anger management, social skills, and self-esteem. A coach will call each participant twice a week to help implement CBTS strategies in daily life. Supportive group therapy SGT for the adolescents will focus on increasing understanding of ADHD, sharing experiences, and fostering a network of support. Calls from a coach will deal with participant-elicited issues. Parents of all adolescents will participate in parallel 6-session support groups similar to SGT and focused on psychoeducation, sharing and support. Treatment effects will be evaluated after 12 weeks of treatment. Maintenance of treatment benefits will be evaluated after 4 and 8 months of follow up. A treatment as usual group will be used to control for repeated measurements. 