The diffusion of new technologies into the market is a critical factor in the success of any technology based company. This paper describes a system dynamics model which integrates a number of key concepts presently used to understand the diffusion process (e.g. technical progress functions, cost-experience curves). It shows how these concepts, together with management decisions regarding R&D investment, marketing, and pricing, drive the evolution of diffusion between technologies. It then illustrates how simulation can be used to understand the critical success factors in technology diffusion, and what this means for the management of technology-based companies.