This book is in some respects a sequel to an earlier volume in this series in which we demonstrated that the new freedoms and responsibilities associated with young adulthood have important impacts on drug use. Those earlier findings, summarized in chapter 2 of this book, give rise to a new set of questions to be answered concerning how changing freedoms and responsibilities relate to changes in drug use during young adulthood. What are the underlying mechanisms? To what extent are the mechanisms—the mediating variables—involved with marijuana use similar to those for cocaine use, or for alcohol use and abuse, or for cigarette use? Similarly, do the different freedoms and responsibilities operate via different or similar mechanisms as they influence smoking, alcohol use, and illicit drug use?
In order to address these new questions, we again employ data from the Monitoring the Future project, which provides a representative sampling of high school graduates who entered young adulthood in the United States during the past two decades. Our data set includes all the measures and respondents used in our previous book, plus a number of additional measures and additional respondents from recent high school classes. Specifically, our samples include members of the high school classes of 1976 through 1997 who participated in follow-up surveys extending (for the older cohorts) throughout their twenties and into their thirties. More than 38,000 of them contributed data for this volume (up from more than 33,000 for the previous volume).