Labour Force Smoking Survey data were used to examine the impact of household environment on the smoking behaviour of youth and young adults. Three indicators of older adult smoking behaviour were used to classify the smoking environment of households. The indicators were smoking prevalence, the mean number of cigarettes smoked per day, and the mean tar yield of cigarettes. Within households, the probability that a young person smokes, how much they smoke, and the type of cigarette they smoke is closely associated with the smoking behaviour of older adults in the household. Household smoking patterns contribute to the overall exposure of family members to the hazards of cigarette smoking and may influence the outcome of smoking cessation programs. Smoking cessation and prevention programs should consider the potential effect of family and household environments.