The Ontario Student Drug Use and Health Survey (OSDUHS) is a population survey of Ontario students in grades 7 through 12. The OSDUHS began in 1977 and is the longest ongoing school survey in Canada, and one of the longest in the world. This self-administered, anonymous survey is conducted across the province every two years with the purpose of identifying epidemiological trends in student drug use, mental health, physical health, gambling, bullying, and other risk behaviours, as well as identifying risk and protective factors. Typically, the OSDUHS surveys thousands of students in over 150 elementary and secondary schools across Ontario. The survey sample is considered representative of all students in grades 7-12 in publicly funded schools in Ontario (just under one million).