Simulation provides valuable benefits starting with the initial phases of a product development project and continuing through providing support for a mature fielded product. By making use of simulation techniques at every stage of the process where they are appropriate, overall product quality can be enhanced while development cycle time and risks are reduced. We will consider the steps in the product development process. In this paper, we will examine the ways simulation can be used in each of these phases to enhance product quality, shorten the development cycle, and reduce project risk.