This bulletin reports the results of a study designed to estimate what proportion of all persons born in New South Wales in 1984 (the cohort) appeared in a NSW criminal court before the age of 21. The results show that 9.9 per cent of the cohort (15.7% of males and 3.8% of females) had at least one court appearance. Most (71.3%) of those who appeared in court before the age of 21 appeared after the age of 18. About a third of the first appearances in court were for driving-related offences but appearances for theft offences, acts intended to cause injury and public order offences were also quite common. The nine per cent of those who appeared in court five times or more, accounted for 36 per cent of the cohort’s court appearances. The 2.3 per cent who appeared in court 10 times or more accounted for 15 per cent of the cohort’s court appearances.