This is the second volume in a two-volume set, presenting findings from the Monitoring the Future study. The first volume presents findings from American secondary students in grades 8, 10, and 12. This second volume contains findings from American college students, their age peers not in college, young adult high school graduates through age 30 (including the college students), and high school graduates ages 35, 40, and 45. Monitoring the Future is a long-term research program conducted at the University of Michigans Institute for Social Research under a series of investigator-initiated research grants from the National Institute on Drug Abuse. It comprises, in part, ongoing series of annual nationally representative surveys of high school seniors (begun in 1975) and of 8th- and 10th-grade students (begun in 1991). Over the years, follow-up surveys have been conducted of representative samples of the previous participants from each high school senior class. The present volume presents 1977 through 2003 follow-up survey results of the graduating high school classes of 1976 through 2002 as these respondents have progressed into adulthood - in fact, up through age 45 for the oldest respondents. In order for this volume to stand alone, some material from Volume I is repeated here. Specifically, chapter 2 in this volume is the same as chapter 2 in Volume I; it provides an integrated overview of the key findings presented in both volumes. Chapter 3, Study Design and Procedures, is also the same as chapter 3, Volume I. Therefore, the reader already familiar with Volume I may wish to skip over these chapters. Otherwise, the content of the two volumes does not overlap.