The principal aim of this work is to investigate the impact of demographic changes on the structure of consumer demand in Austalia. The study utilizes the demand system approach and a particular form of the model is chosen which incorporates and generalizes certain features of other existing models. The choice of model is designed to take the best advantage of the data set available and some of the data required have been specifically constructed for the purpose of this study. Certain econometric techniques have been developed, in particular, a technique for estimating an error components model from combined time-series and aggregated cross-section data. Finally, the results are presented which describe, with a high level of detail, the effect of demographic variables on consumer demand in Australia. The usefulness of the results is demonstrated in a number of important applications.