Substance use is a leading cause of preventable morbidity and mortality; it is in large part why, among 17 high-income nations, people in the U.S. have the highest probability 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. It warrants sustained attention. 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. Since its onset in 1975, MTF has been continuously funded by the National Institute on Drug Abuse--one of the National Institutes of Health--under a series of peer-reviewed, competitive research grants. The 2017 survey, reported in this report, is the 43rd consecutive survey of 12th grade students and the 27th such survey of 8th and 10th graders. This annual monograph series has been a primary vehicle for disseminating MTF's epidemiological findings. This monograph presents the results of the 43rd survey of drug use and related attitudes and beliefs among American high school seniors and 27th such survey of 8th and 10th grade students. The next monograph in this series will report the 38th such survey of American college students and same-age youth who do not attend college, as well as findings regarding substance use prevalence and trends among adults through age 60. An annual monograph on risk and protective behaviors for the spread of HIV/AIDS2 among young adults was added beginning in 2009. (In years prior to 2009, findings from the study on risk and protective behaviors related to the spread of HIV/AIDS were contained in "Volume II.") [For the report from the previous year "Monitoring the Future National Survey Results on Drug Use, 1975-2016. Volume I, Secondary School Students," see ED578730. For Volume II "Monitoring the Future National Survey Results on Drug Use, 1975-2017. Volume II, College Students & Adults Ages 19-55," see ED589764. For "Demographic Subgroup Trends among Adolescents in the Use of Various Licit and Illicit Drugs, 1975-2017. Monitoring the Future Occasional Paper Series. Paper 90," see ED589759. For "Monitoring the Future National Survey Results on Drug Use, 1975-2017: Overview, Key Findings on Adolescent Drug Use," see ED589762.]