Young adults with attention-deficit/hyperactivity disorder (ADHD) symptoms are more likely than their peers to engage in risk-taking behaviors, including harmful alcohol use, consumption of illicit drugs, and risky sexual behaviors. These behaviors become more common in the general population of young adults as they enter college, particularly for those who join social groups such as Greek life and athletics. It is unclear whether the presence of significant ADHD symptoms is related to engagement in risky behaviors particularly among students who participate in various social activities. We examined: (a) the degree to which inattentive and hyperactive-impulsive symptoms predict risk-taking behavior for a sample of 395 college students, and (b) whether the relationship between ADHD symptoms and risk-taking behavior is moderated by participation in social activities. Results indicated that more significant ADHD symptoms are associated with increased risk-taking behaviors, including harmful alcohol consumption, illicit drug use, and risky sexual behavior. Additionally, social group membership was predictive of increased risk-taking in some cases, particularly for students affiliated with Greek organizations. Findings demonstrate the need for universities to implement preventive programs for students with ADHD symptoms and those in social groups, especially Greek life, to minimize the likelihood of negative outcomes associated with risk-taking.