Objective: The purpose of the current investigation is to examine the characteristics of college students with attention-deficit hyperactivity disorder symptoms who misuse their prescribed psychostimulant medications. Methods and Participants: Forty-three undergraduate students with a prescription for Ritalin or Adderall completed structured interviews and a battery of questionnaires. Results: Analyses revealed that compared to non-misusers, misusers were significantly more likely to report using a greater number of illicit substances, including nicotine, marijuana, cocaine, hallucinogens, and opiates, over the past year. Additionally, compared to non-misusers, misusers were significantly more likely to report greater negative expectancies effects, experience more hyperactivity symptoms, and score higher on a measure of sensation seeking. Conclusion: The findings have important implications for future prevention initiatives. In particular, knowledge regarding the extent of misuse in populations with and without prescriptions and variables associated with misuse is essential to the development of effective prevention programs. (Contains 2 tables.)