The United States Monitoring the Future Survey, 8th and 10th Grade Students 1999 is part of the Monitoring the Future Study, a nationally representative annual study of students enrolled in public and private high schools in the United States. Begun in 1975 as a survey of 12th grade students, 8th and 10th grade surveys were added to the series in 1991. Monitoring the Future (MTF) surveys provide information on the attitudes and behaviors of students on the use and abuse of substances such as alcohol, tobacco, and illicit and prescription drugs. The MTF study is designed so that changes in attitudes and behaviors can be observed across time. Participants in the MTF 1999 (8th/10th Grade) survey include 17,287 8th grade students from 120 public schools and 30 private schools, and 13,885 10th grade students from 117 public schools and 23 private schools.