A high prevalence of comorbidity of ADHD and substance-use disorders (SUDs) has been shown in the literature. In this article, the literature for the treatment of adolescents and adults with co-occurring ADHD and SUD is examined. Findings from pharmacotherapy suggest mild improvement in ADHD without demonstrable changes in SUD unless the addiction was stabilized prior to treating the ADHD. No unique adverse effects, worsening of SUD, misuse or diversion of stimulants are reported in the included studies. Treating ADHD pharmacologically in individuals with ADHD plus SUD only has a modest impact on ADHD and SUD that is not observed in controlled trials. Limited data in adults with ADHD and brief abstinence of their SUD showed improvements in both ADHD and SUD with treatment. Further studies of cognitive behavioral therapy, sequencing of therapies and longer term treatment outcomes for groups with ADHD and active SUD are necessary.