This paper used survey data from Victoria, Western Australia and Queensland to examine and explain alcohol and drug use in school-aged Australian children. Youth self-reports for surveys from 41,328 adolescents , with an average age of 13.5 years were examined. Alcohol, tobacco and cannabis use significantly declined from 1999 to 2015. Two major factors were identified as contributing to the decline in substance use. First, parents have a less favourable attitude to supplying alcohol to their children, and second, lower availability of substances as more outlets are tightening up their restrictions on serving minors.