Monitoring the Future (MTF), now in its 35th year, has become one of the nation's most relied-upon sources of information on changes taking place in licit and illicit psychoactive drug use among American adolescents, college students, young adults, and more recently, middle-aged adults. During the last three and a half decades, the study has tracked and reported on the use of an ever-growing array of such substances in these populations. This annual series of monographs is one of the major vehicles by which the epidemiological findings from MTF are reported. Findings from the inception of the study in 1975 through 2009 are included--the results of 35 national in-school surveys and 33 national follow-up surveys. MTF has conducted in-school surveys of nationally representative samples of (a) 12th-grade students each year since 1975 and (b) 8th- and 10th-grade students each year since 1991. In addition, beginning with the class of 1976, the project has conducted follow-up mail surveys on representative subsamples of the respondents from each previously participating 12th-grade class. These follow-up surveys now continue well into adulthood. A number of important findings have been summarized in this report to provide the reader with an overview of the key results. Because so many populations, drugs, and prevalence intervals are discussed here, a single integrative set of tables (Tables 2-1 through 2-4) show the 1991-2009 trends for all drugs on five populations: 8th-grade students, 10th-grade students, 12th-grade students, full-time college students modal ages 19-22, and all young adults modal ages 19-28 who are high school graduates. (Note that the young adult group includes the college student population.) "Volume II" also contains data on older age bands based on the longer term follow-up surveys: specifically, ages 35, 40, 45, and 50. An index is included. (Contains 30 tables, 74 figures, and 64 footnotes.) [For Volume I, see ED514370.]