All search in the real-world is inherently interactive. Information retrieval (IR) has a firm tradition of using simulation to evaluate IR systems as embodied by the Cranfield paradigm. However, to a large extent, such system evaluations ignore user interaction. Simulations provide a way to go beyond this limitation. With an increasing number of researchers using simulation to evaluate interactive IR systems, it is now timely to discuss, develop and advance this powerful methodology within the field of IR. During the SimInt 2010 workshop around 40 participants discussed and presented their views on the simulation of interaction. The main conclusion and general consensus was that simulation offers great potential for the field of IR; and that simulations of user interaction can make explicit the user and the user interface while maintaining the advantages of the Cranfield paradigm.