OBJECTIVES:To analyse trends in smoking initiation and prevalence among young Aboriginal and Torres Strait Islander people (Indigenous people) to identify which stages of adolescence and young adulthood prevention activities should target. METHODS:Secondary analysis of 'daily smoking' and 'never smoked' responses from Indigenous people aged 15 years and older in five national Indigenous surveys from 2002 to 2014-15, and of initiation age among those aged 18 years and older in 2004-05 and 2012-13. RESULTS:Smoking prevalence among 15-24-year-olds declined significantly between 2002 and 2014-15, falling 14 percentage points (95%percnt; confidence interval [CI] 8, 21) from 45%percnt; to 31%percnt;. The greatest decline was among 18-19-year-olds, with a decrease of 17 percentage points (95% CI 4, 29) from 48%percnt; to 31%percnt;. The proportion of 15-24-year-olds who had never smoked increased significantly, by 12 percentage points (95%percnt; CI 6, 18) from 44%percnt; in 2002 to 56%percnt; in 2014-15. Between 2004-05 and 2012-13, the proportion of 18-24-year-old smokers who had started daily smoking before the age of 18 years declined significantly, down 8 percentage points (95%percnt; CI 2, 15) from 84%percnt; to 76%percnt;. In 2012-13, 24%percnt; of smokers aged 18-24 years started daily smoking after age 18, half (49%percnt;) started between 15 and 18 years, and around a quarter started before age 15. CONCLUSIONS:There have been significant declines in smoking prevalence among young Indigenous people between 2002 and 2014-15 as fewer take up smoking. Smoking initiation occurs over a wide age range. The majority of daily smokers started before the age of 18; however, initiation may be delayed until early adulthood for an increasing number. The challenge for tobacco prevention is to reach young people in early adolescence and continue to reinforce smoke-free intentions into young adulthood.