With the recent increase in the scope of drug and alcohol problems has come an awareness of the need for solutions. In this context, federal support for research on drug problems increased tremendously during the last 10 to 15 years with the establishment of the National Institute on Drug Abuse (NIDA) and the National Institute on Alcohol Abuse and Alcoholism (NIAAA). Funding from these and other sources has led to a substantial increase in the quantity and quality ofpublished work related to substance abuse. As data accumulate, it is becoming more apparent that substance abuse problems are extremely complex and are influenced by a variety ofbiological psychological, and environmental variables. Un fortunately it has proved difficult to go beyond this conclusion to a de scription of how these multiple factors work tagether to influence the development of, and recovery from, drug and alcohol dependence. The purpose of this book is to try to meet that objective by including, in one volume, Iiterature reviews and theoretical analyses from a wide variety of drug researchers. We chose the authors in an attempt to assure that each of the various Ievels of analysis appropriate to the substance abuse problems would be included. In each case, the author was asked to consider how the variables in is or her particular domain might con tribute to the appearance of individual differences in both alcohol and drug problems.