The Australian Temperament Study is a major longitudinal study following a cohort of Australians from birth to (so far) early adulthood. Measures of own and parents' alcohol, tobacco and other drug use have been taken in age appropriate ways throughout. This collaborative project will seek to examine early risk factors for later drug use, risky use and actual harm. To date, such studies have focused on predicting whether adolescents will use drugs rather than whether they will engage in risky levels of use. One focus will be to see whether the Prevention paradox applies to these data: will most use, risky use and harm be concentrated in a high risk group of (broadly) disadvantage children or in the wider population of mostly low risk, well-adjusted children?