Recent well-designed studies involving standardized diagnostic instruments and random surveys of American households have provided informative data as to the current prevalence of alcohol abuse/dependence in the United States. Data from three epidemiological sites are reviewed, and the breakdown of alcohol abuse/dependence by age, sex, and race is presented. The criteria for the diagnosis of alcoholism are reviewed. Recent emphasis on the use of laboratory studies is addressed, and the need for caution in relying on laboratory results is emphasized. The importance of a careful history and the need to develop a relationship with the patient and family members is noted. Current biological findings in regard to alcoholism include the effect of alcohol on the cell membrane and the evidence, as well as lack of evidence, for genetic contributions to alcoholism. The Tetrahydroisoquinoline (THIQ) theory is briefly reviewed and cautionary remarks concerning premature emphasis on this theory are made.