How can we develop innovative concepts? The purpose of this paper is to investigate how generative prototype sessions can elicit so-called tacit and latent knowledge from participants through interaction and play. To illustrate this, a session from the design process will be described along with a brief take on current theories. It is discussed how practical tools and methods along with the dynamics occurring during such a session can translate actor knowledge to become useful throughout a the entire design process. The paper concludes that knowledge gained from generative prototype sessions is an indiscernible blend of different types of knowledge, but that tacit and latent constitutes an important part.