Cost is the underlying driving force that has created the RIM market and that will determine the future growth of reaction injection molding. This paper examines the current status of the RIM market, the manufacturing process, and RIM polymers as they relate to part economics. This examination shows that, while RIM is today a competitive alternative to mold large; complex; painted parts, an opportunity exists to substantially improve the economic viability of both RIM, the product and RIM, the manufacturing process. Development programs are described which are designed to lower part costs, and the potential- savings from these programs are quantified.