The etiology of alcoholism in women is no longer a question of nature or nurture. Most observers would agree that alcoholism, both male and female, is mediated by genetic factors. The question is how much of the variance is explained by genetic factors and to what degree is this genetically mediated disorder moderated by personal characteristics of the woman. Among the most salient personal characteristics moderating the genetic vulnerability may be factors such as age, ethnicity, and presence of psychiatric comorbidity. Cultural factors and familial environmental factors are most likely predictors as well. Therefore, the chapter will discuss the genetic epidemiology of alcoholism in women. Genetic heterogeneity will be discussed and evidence presented that suggests the existence of two forms of alcoholism in women: one more environmentally determined and one more influenced by genetic mediation. Evidence for the existence of a genetic diathesis in women will be presented, noting extant literature involving twin and adoption designs. Suggestions for what might be transmitted from generation to generation (e.g., neurobiological factors, temperament) with special reference to preadolescent and adolescent girls will also be discussed.