 Attention deficit hyperactivity disorder ADHD is one of the most common co-occurring psychiatric disorders 30-50 in adolescents with substance use disorders SUD. Yet, little is known about the safety and efficacy of medications for ADHD in adolescents with SUD, since such youths have been excluded from most medication trials. Clinicians are therefore understandably reluctant to treat ADHD in substance abusing adolescents, often first referring such youths to substance treatment. Untreated ADHD is associated with poorer substance treatment outcomes. We address this research gap by proposing a randomized controlled trial of bupropion vs placebo in 130 adolescents 13-19 years with Diagnostic and Statistical Manual DSM IV ADHD, nicotine dependence and cannabis use disorder not excluding other SUD. Participants in both bupropion and placebo treatment groups will receive weekly individual manualized-standardized cognitive behavioral therapy CBT targeting SUD at no cost to them throughout the 16 weeks of the medication trial. Bupropion also is effective in treating nicotine dependence in adults; the majority of adolescents with marijuana and other drug abuse also smoke tobacco. More recent research in adults indicates that bupropion may reduce craving and use of other substances of abuse e.g. methamphetamine, cocaine. Its possible impact on cannabis use disorder the addiction for which most teens are referred to treatment has not yet been evaluated. However since all drugs of abuse have a final common pathway leading to addiction via action in the so called brain reward system ventral tegmental area VTA, accumbens -an important secondary aim is to evaluate bupropions potential impact on craving and use of marijuana MJ in addition to its known similar action on nicotine. 