One-of-a-kind production (OKP) is a new manufacturing paradigm to produce customized products based on requirements of individual customers while maintaining the quality and efficiency of mass production. In this research, an integrated optimal product design and process planning approach is developed to satisfy customer requirements considering design and manufacturing constraints. In this work, a hybrid AND-OR graph is introduced to model the variations of design configurations/parameters and manufacturing processes/parameters in generic product family. Since different design configurations and parameters can be created from the same customer requirements, and each design can be further achieved through alternative manufacturing processes and parameters, co-evolutionary genetic programming and numerical optimization are employed to identify the optimal product design configuration/parameters and manufacturing process/parameters. An industrial case study to identify the optimal design configuration/parameters and manufacturing process/parameters of custom window products in a local company is introduced to demonstrate the effectiveness of the developed method.Copyright © 2008 by ASME