Athletes use substances to produce pleasure, relieve pain and stress, improve socialization, recover from injury, and enhance performance. Therefore, they use some substances in substantially higher rates that nonathletes. Despite these higher rates of use, rates of addiction may in fact be lower in athletes. This article reviews the prevalence and patterns of use, health and performance effects, and preventive and treatment interventions for alcohol, tobacco, stimulants, and steroids. Each substance is considered from the differing perspectives of abuse/addiction and performance enhancement models. Similarities and differences between college and professional athletes are discussed. Finally, suggestions for future research are made.