The majority of studies concerning diffusion or product growth of consumer durables have treated the U.S. market as a whole and have applied the diffusion model on the assumption that the market exhibits a homogeneous response in its diffusion process. If the market is heterogeneous, however, an aggregate model entails a misspecification problem which could adversely affect the applicability and efficiency of the model. A modeling framework is developed for analyzing the diffusion process in a possibly heterogeneous market. Empirical analysis using data on the videocassette recorder (VCR) market reveals that the modeling framework captures to a fair extent heterogeneous diffusion processes across different regions in the U.S. market. Managerial implications are derived and discussed.