The percentage of adolescents reporting substance use decreased significantly in 2021, according to the latest results from the Monitoring the Future survey of substance use behaviors and related attitudes among eighth, 10th, and 12th graders in the United States. In line with continued long-term declines in the use of many illicit substances among adolescents previously reported by the Monitoring the Future survey, these findings represent the largest one-year decrease in overall illicit drug use reported since the survey began in 1975. The Monitoring the Future survey is conducted by researchers at the University of Michigan, Ann Arbor, and funded by the National Institute on Drug Abuse (NIDA), part of the National Institutes of Health. The 2021 survey reported significant decreases in use across many substances, including those most commonly used in adolescence – alcohol, marijuana, and vaped nicotine. The 2021 decrease in vaping for both marijuana and tobacco follows sharp increases in use between 2017 and 2019, which then leveled off in 2020. This year, the study surveyed students on their mental health during the COVID-19 pandemic. The study found that students across all age-groups reported moderate increases in feelings of boredom, anxiety, depression, loneliness, worry, difficulty sleeping, and other negative mental health indicators since the beginning of the pandemic.