Full Stage Lay Summary Alcohol is a leading cause of morbidity and mortality in New Zealand with youth disproportionally affected. Imminent change to our alcohol policy environment has created the opportunity for this research. The Alcohol Policy Interventions in New Zealand (APINZ) study will evaluate changes in alcohol policy on drinking behaviour and policy related mediating variables. It uses a longitudinal design, interviewing a sample of the general population and of young people. By examining impacts of policy change on variables such as where and when alcohol is purchased and consumed and who supplies underage young people we will better understand the behavioural, social and environmental processes that underpin health in relation to alcohol use. APINZ is part of an international project which will allow comparisons to be made with other countries. It will provide new knowledge about impacts of alcohol policy change and contribute to national and international efforts to reduce alcohol-related harm.