The question how agent and patient roles are assigned to causal participants has largely been neglected in the psychological literature on force dynamics. Based on the linguistic theory of Dowty (1991), we propose that agency is a prototype concept. We adapted Dowty’s theory to account for scenarios showing physical interactions. In the standard Michotte launching scenario the ball entering the scene is usually assigned the agent role, whereas the ball that is being launched is viewed as the patient. We showed in two experiments that agency intuitions were moderated by manipulations of the context prior to the launching event. Altering features such as relative movement, sequence of visibility, and self-propelled motion tended to increase agency attributions to the patient relative to the standard scenario. We suspect that shifts in figure-ground perceptions, and intuitions about characteristics of interventions may be the overarching reason for the efficacy of the tested criteria.