This article extends the literature on time series estimation of U.S. consumer demand by presenting a coherent theoretical structure with a multi-period planning horizon for consumer choice and a more general treatment of the aggregation problem that allows the possibility that consumers' tastes change over time and vary across individuals. Based on our theoretical model, an econometric model is used to obtain estimates in a multi-period context of U.S. demand for imported foods and domestically produced foods. The hypothesis that current purchases depend on expected future prices is supported by the empirical results for imported foods.