Abstract
Our concern is with how interaction with customers affects knowledge creation in product development projects. Customers have a crucial role in stimulating innovation, but previous research has not identified what effects the interaction has on knowledge creation nor at what point in time interaction with customers should be sought. Through case research in high velocity industries we
identify the effect customer interaction has on knowledge creation processes inside new product development projects and therefore ultimately innovation. In particular we highlight the effects the interaction has on tacit and explicit knowledge, and the need to acknowledge the difference between the two.