This paper considers the concept selection stage of a new product development process, using as a point of departure previous work in marketing on optimal concept selection utilizing product attribute-based customer preference and product cost models. We offer empirical support for the need to push beyond these models into more complete “customer-ready” prototypes before choosing a concept to commercialize. Although the correlations between attribute-based predictions on the one hand, and customer preferernces and product costs on the other, are significant and substantial, too much variance is left unexplained t rely on these models in isolation. This implies that more detailed design work should be performed on several concepts in paralel. We also provide a road map for concept generation and selection that leverages the unique strengths of marketing, design and manufacturing in developing successful products.