AbstractThis overview discusses the five papers covering demographic and prevalence issues in terms of the commonalities and differences across psychoactive substances, particularly as they pertain to the relationship between demographic factors and the prevalence of substance abuse. This overview also concerns itself with gaps in knowledge, methodological issues and future directions for research. It begins with some basic definitions and fundamental questions. A brief review of the salient points of each paper is then provided, followed by a more synthetic discussion of methodological and theoretical issues. It closes with some speculative ideas about the meaning of demographic variables for an understanding of substance abuse.