This article explores the drivers of product development performance in a rapidly changing environment. Effective product developers in turbulent environments, such as Silicon Graphics and NEC, provide a contrast to traditional product development. They exhibit a development process characterized by extreme flexibility and responsiveness. This, in turn, hinges on the capability to gather and rapidly respond to new knowledge about technical and market information as a project evolves. Instead of focusing on execution and implementation, these companies' development process emphasizes the importance of the concept development stage, while keeping the product's specification fluid as late as possible in a project. This ensures the best match between system and component technologies, as well as the maximum flexibility to respond to changes.