OBJECTIVE: Adolescent alcohol consumption has declined in Australia over the past 20 years. Secondary supply laws (SSLs) typically prohibit the supply of alcohol to adolescents by persons other than parents or guardians, or without parental consent. SSLs were introduced in Australia at different times in different states and territories over the period of declining alcohol consumption. In this study we examined the impact of variations in SSLs across Australia on young people’s drinking. METHOD: We used six waves of the National Drug Strategy Household Survey, a cross-sectional survey of the Australian population, from 2001 to 2016. The study population was adolescents ages 14-17 years. Our primary measure of interest was exposure to SSLs. Data were analyzed using two-way linear and logistic regression models with fixed effects of Australian state/territory and time to identify the effect of SSLs on the frequency of drinking, past-year drinking, and the secondary supply source, respectively. RESULTS: We found no evidence of an association between SSLs and any of the three outcomes of interest. CONCLUSIONS: SSLs are challenging to enforce, and, although they may empower parents to have more control over their children’s drinking, they were not associated with reductions in adolescent drinking in Australia. Researchers looking to explain the decline in adolescent drinking in Australia should investigate factors beyond SSLs.