Monitoring the Future (MTF) is designed to give such attention to substance use among the nation's youth and adults. It is an investigator-initiated study that originated with, and is conducted by, teams of research professors at the University of Michigan's Institute for Social Research. MTF contains ongoing national surveys of both adolescents and adults in the United States. It provides the nation with a vital window into the important but often hidden problem behaviors of use of illegal drugs, alcohol, tobacco, and psychotherapeutic drugs used without a doctor's orders. For nearly five decades, MTF has helped provide a clearer view of the changing topography of these problems among adolescents and adults, a better understanding of the dynamic factors that drive some of these problems, and a better understanding of some of their consequences. It has also given policymakers, government agencies, public health professionals, and nongovernmental organizations (NGOs) in the field some practical approaches for intervening.