In this paper we look at the behaviour of households as far as participation and rate of consumption of tobacco are concerned using cohort data from the Spanish Continuous Family Expenditure Survey during the period 1985-94. We test the results, in statistical and economic terms, from several estimators on samples with different levels of aggregation and offer evidence on the different behaviour of households according to several demographic characteristics. The results suggest that the effect of legislative measures cannot be identified when participation and consumption are not separately considered. Once we do so, these measures seem to affect participation alone.