It is suggested that alcohol, like so many other drugs, is consumed for its rewarding and tension-reducing effects. The progression from use to abuse has many initiating and perpetuating causes at different levels of biological organization, ranging from the molecular to the behavioral level. The interactions between the many causes are better appreciated when they are conceptualized as originating at and progressing from one level to another. Among the perpetuating causes of alcohol abuse may be some of its consequences such as medical diseases and physical dependence. It is hypothesized that at the molecular level an acquired or inherited deficiency of anxiolytic synaptic receptors may be one of several causes of alcohol abuse.