This article presents the proceedings of a symposium held at the June 2005 meeting of the Research Society on Alcoholism in Santa Barbara, California. Impaired control over substance use has long been considered a central feature of alcohol and drug dependence. However, much remains to be learned about the nature of impaired control, the mechanisms by which acute and chronic substance use can lead to impaired control, and how this construct is best assessed in the laboratory and the clinic. The goal of this symposium was to describe current perspectives on impaired control over alcohol and drug use from diverse research areas, to promote future multidisciplinary work in this area. Four speakers described their work on impaired control using human clinical samples (Dr. Chung), animal models (Dr. Miczek), experimental laboratory paradigms in humans (Dr. Fillmore), and neuroimaging studies (Dr. Easdon). Taken together, the talks highlighted the heterogeneous nature of constructs such as impaired inhibitory control, and patterns of impulsive and compulsive substance use. Future clinical and experimental research should attempt to carefully define and measure particular aspects of impaired control and to seek insights from other disciplines.