The new biopsychosocial disease model of alcoholism is examined from the perspective of recent biologic research. Studies of animal and human genetic predispositions suggest the presence of genetic influences over drinking behavior as well as biologic risk factors related to deficiencies in various neurochemicals. Ethanol affects the fluidity of cell membrane lipids, eventually causing membrane dysfunction. It also adversely affects the activity of two enzymes, monoamine oxidase and adenylate cyclase, that have important functions in the information processing system of the brain. Research on condensation products formed in the brain after alcohol consumption has provided clues to the development of alcoholism, but many questions remain unanswered. Alcoholism is clearly a multidimensional phenomenon in which biologic, psychological, and sociocultural factors interact to produce illness.