Modeling and gaining an understanding of the interaction between information from design and from manufacturing is an important step in developing techniques and methods for concurrent engineering. In this paper, the role of optimization techniques in the product development process in a concurrent engineering framework is examined. Through arguments based in optimization theory, it is demonstrated that a concurrent approach to designing for manufacture problems is superior to a sequential one. By extension, this applies to designing for other life-cycle processes. Results which illustrate the point are presented from a comprehensive, non-textbook case study in design using composite materials and dealing with the integration of analysis, dimensional synthesis, and manufacturing. The case study is tackled by using Decision Support Problems. The focus in the paper is on understanding the ramifications of considering life-cycle processes concurrently.