This paper examines the association between the smoking and drinking behaviours of parents and their adolescent children, and the effect of gender and social class upon this association. It is based on data collected from a cohort of young people and their parents, resident in the west of Scotland. Both social class and parental smoking behaviour were independently associated with young people's smoking, with young people from lower social class households or whose parents smoked being most likely to smoke. Social class and gender were independently associated with young people's drinking, with males and young people from non-manual households being most likely to drink. Parental drinking behaviour was associated positively with young people's drinking only in non-manual classes and among daughters. We conclude that it is important to take social class and gender into account since it may influence whether or not there is an association between the behaviour of young people and that of their parents, and it may influence young people's behaviour in addition to influences from parental behaviour.