Monitoring the Future (MTF), which is now in its 36th year, is a research program conducted at the University of Michigan's Institute for Social Research under a series of investigator-initiated research grants from the National Institute on Drug Abuse. The study is comprised of several ongoing series of annual surveys of nationally representative samples of 8th- and 10th-grade students (begun in 1991), 12th-grade students (begun in 1975), and high school graduates into adulthood (begun in 1976). The current monograph reports the results of the repeated cross-sectional surveys of high school graduates since 1976 as the authors follow them into their adult years. Several segments of the general adult population are covered in these follow-up surveys: (1) American college students; (2) Their age peers who are not attending college, sometimes called the "forgotten half"; (3) All young adult high school graduates of modal ages 19 to 30, which the authors refer to as the "young adult" sample; and (4) High school graduates at the specific later modal ages of 35, 40, 45, and 50. Changes in substance abuse and related attitudes and beliefs occurring at each of these age strata receive particular emphasis. The authors can summarize the findings on trends as follows: For more than a decade--from the late 1970s to the early 1990s--the use of a number of illicit drugs declined appreciably among 12th-grade students, and declined even more among American college students and young adults. These substantial improvements--which seem largely explainable in terms of changes in attitudes about drug use, beliefs about the risks of drug use, and peer norms against drug use--have some extremely important policy implications. One clear implication is that these various substance-using behaviors among American young people are malleable--they can be changed. It has been done before. The second is that demand-side (rather than supply-side) factors appear to have been pivotal in bringing about most of those changes. The levels of marijuana availability, as reported by 12th graders, have held fairly steady throughout the life of the study. (Moreover, among students who abstained from marijuana use, as well as among those who quit, availability and price rank very low on their lists of reasons for not using.) And, in fact, the perceived availability of cocaine was actually rising during the beginning of the sharp decline in cocaine and crack use in the mid- to late- 1980s, which occurred when the perceived risk associated with that drug rose sharply. However, improvements are surely not inevitable; and when they occur, they should not be taken for granted. Relapse is always possible and, indeed, just such a relapse in the longer term epidemic occurred during the early to mid-1990s, as the country let down its guard on many fronts. The drug problem is not an enemy that can be vanquished. It is more a recurring and relapsing problem that must be contained to the extent possible on an ongoing basis. Therefore, it is a problem that requires an ongoing, dynamic response--one that takes into account the continuing generational replacement of children, the generational forgetting of the dangers of drugs that can occur with that replacement, and the perpetual stream of new abusable substances that will threaten to lure young people into involvement with drugs. (Contains 30 tables, 49 figures and 68 footnotes.) [For related reports, see "Monitoring the Future National Survey Results on Drug Use, 1975-2010. Volume I, Secondary School Students" (ED528081); and "Monitoring the Future National Results on Adolescent Drug Use: Overview of Key Findings, 2010" (ED528077).]