Abstract: Pen/Stylus input systems are constrained by the limited input capacity of the electronic stylus. Stylus modes, which allow multiple interpretations of the same input, lift capacity limits, but confront the user with possible cognitive and motor costs associated with switching modes. This paper examines the costs of bimanual mode switching, in which the non-preferred hand performs actions that change modes while the preferred hand executes gestures that provide input. We examine three variants to control mode of a stylus gesture: pre-gesture mediation, post-gesture mediation, and mediation that occurs concurrently with stylus gesturing. The results show that concurrent mode-switching is faster than the alternatives, and, in one trial, marginally outperforms the control condition, un-moded drawing. These results demonstrate an instance in which suitably designed mode-switching offers minimal cost to the user. The implications of this result for the design of stylus input systems are highlighted.