While there is increasing evidence that involving suppliers in new product development (NPD) is important, and for many firms even inevitable, there is also evidence that not all such efforts are successful. Firms aiming at implementing this strategy effectively have to pay close attention to several contingency factors on the organizational level and properly manage supplier involvement on the project level. The exploratory case study research underlying this article explores key issues to be considered when involving suppliers in NPD and the counter measures they can take. Our research shows that companies differentiate between so-called “know-how” and “capacity” projects, and that they manage them differently. Furthermore, this research shows that firms outside the automotive and high-tech manufacturing industries are likely to intensify supplier involvement in the future.