The purpose of the present study was to determine the role of emotion regulation in the pathway to problematic alcohol use among adolescents with attention-deficit/hyperactivity disorder (ADHD), specifically investigating the total effect of emotion regulation on problematic alcohol use and the indirect effect of emotion regulation through social skills on problematic alcohol use within a 2-wave longitudinal design. The potential protective effect of parent knowledge of these effects was assessed. Participants were 149 adolescents with ADHD (mean [M] 15.11 years old; 78% male), and approximately 19% endorsed problematic alcohol use at Time 2. Contrary to our hypothesis, emotion regulation was not associated with subsequent problematic alcohol use without social skills in the model, and parent knowledge did not moderate this pathway. The results supported an indirect effect of emotion regulation on problematic alcohol use via social skills, although the direction of this effect was unexpected. Greater emotion regulation skills were associated with greater social skills, which in turn were associated with a higher likelihood of problematic alcohol use. Parent knowledge was protective against this indirect effect, such that the indirect effect was only present in the context of low parent knowledge. The findings delineate the roles of risk and protective factors associated with the progression from experimentation to alcohol use disorder among adolescents with ADHD. [This is the online version of an article published in "Psychology of Addictive Behaviors" (ISSN 0893-164X).]