AbstractAn econometric model of the demand and supply of color televisions, black and white televisions and video cassette recorders in the United States from 1964 to 1985 is developed and estimated. Supply and demand parameter estimates are obtained using a simultaneous equation system estimated by three‐stage least squares. The model employed integrates theories of product diffusion from the marketing literature with those of the economic literature on discrete choice. Particular attention is paid to the relationship between product saturation and demand, as well as to supply decisions pertaining to product differentiation and the timing of new product introduction. The central hypothesis that product differentiation and new product introduction are more likely to occur as demands for established products slow at critical saturation levels is supported by the empirical results and actual market occurrence