We recruited 211 undergraduates to rate the degree to which each of 34 listed reasons for not taking drugs had influenced their abstinence from MDMA/ecstasy, cocaine, marijuana, and hallucinogens. Participants rated reasons such as personal and family medical histories, religion, and physiological consequences of drug use as having little or no impact on abstention from all four substances. Consistent with previous research and developmental theory, concerns about drug-induced impairment and drug use being contrary to one's self-image reportedly inhibited students' consumption of notably different types of illicit substances. (Contains 6 tables.)