Substance use is a leading cause of preventable morbidity and mortality, and it is in large part why people in the U.S. have the highest probability among 17 high-income nations of dying by age 50. Substance use is also an important contributor to many social ills including child and spouse abuse, violence more generally, theft, suicide, and more; and it typically is initiated during adolescence. Monitoring the Future (MTF) is designed to give sustained attention to substance use among the nation's youth and adults. It is an investigator-initiated study that originated with and is conducted by a team of research professors at the University of Michigan's Institute for Social Research. The 2014 survey, reported here, is the 40th consecutive survey of 12th-grade students and the 24th such survey of 8th and 10th graders. Two of the major topics included in the present volume are: (1) the prevalence and frequency of use of a great many drugs among American secondary school students in 8th, 10th, and 12th grades; and (2) historical trends in use by students in those grades. Distinctions are made among important demographic subgroups in these populations based on gender, college plans, region of the country, population density, parent education, and race/ethnicity. MTF has demonstrated that key attitudes and beliefs about drug use are important determinants of usage trends, in particular the amount of risk to the user perceived to be associated with the various drugs and disapproval of using them; thus, those measures also are tracked over time, as are students' perceptions of certain relevant aspects of the social environment--in particular, perceived availability, peer norms, use by friends, and exposure to use by others of the various drugs. Data on grade of first use, discontinuation of use, trends in use in lower grades, and intensity of use are also reported. [For "Monitoring the Future National Survey Results on Drug Use, 1975-2014. Volume 2, College Students & Adults Ages 19-55," see ED578455.]