In 1999, the New Zealand Parliament lowered the minimum age at which people could legally purchase or drink alcohol on licensed premises from 20 years with a number of exemptions to 18 years with one exemption. This report, the fourth in a series, presents some statistics on the possible effects of the Sale of Liquor Amendment Act of 1999, focusing on the lowering of the purchase age. The report presents a new statistical series on the number of liquor licenses. The statistics are indicators, which when assessed together, give some insight into the possible impact of lowering the purchase age. The statistics show a mixed picture of the possible impact of lowering the purchase age. Some of the indicators, such as minors drinking or possessing alcohol in public places, prosecutions of young people for driving with excess breath or blood alcohol, and crashes where alcohol was recorded as a factor indicate that the change in legislation may have had a detrimental effect on young people’s drinking behavior. Overall it is not clear to what extent any of the changes can be attributed to the changes in legislation. Tables