Available evidence suggests that drinking habits, as well as the patterns of use of other drugs, in Northern Ireland are markedly different from those in Britain. In order to investigate these differences amongst young people, a cross-national study was conducted of self-reported alcohol and tobacco and illicit drug use amongst 1172 secondary school pupils in Northern Ireland and Scotland. Two age groups were included: 11-12 years old and 14-16 years old. It was intended that this would enable not only the comparison of national attitudes, behaviour and beliefs relating to use and misuse of alcohol, tobacco and illicit drugs, but also an examination of how such variables may change during the early teenage years. The study group was also divided by gender, socio-economic status and religious affiliation. In line with other studies of teenage alcohol use, these data showed that use of alcohol increased with age and that males were more likely than females to drink, and to drink heavily. The results of this study also supported earlier findings that Northern Irish teenagers were less likely than their Scottish counterparts to have consumed an alcoholic drink. However, those that did drink were more likely than their British peers to be heavy drinkers and to consume alcohol in contexts associated with possible dangers, i.e. drinking in peer groups in uncontrolled settings. It was shown, that in Northern Ireland only, those attending Roman Catholic schools were less likely to consume alcohol. Again, in the Northern Ireland only, those from less affluent backgrounds were more likely than their wealthier counterparts to drink and also more likely to be heavier drinkers. The use of tobacco and illicit drugs also increased with age. Although the males in this study were more likely to have used illicit drugs, in relation to smoking no gender effect was observed amongst the Scottish study group.