Bisimulation and bounded bisimulation Jelle Gerbrandy In this paper the notion of bounded bisimulation is introduced to explore connections between work on Kripke models, non­well­founded sets and knowledge structures. The paper is organized as follows. The next section contains definitions of bisimulation and bounded bisimulation on Kripke models, which are the core notions in this paper. The next two sections contain definitions of non­well­founded models for modal logic, and of knowledge structures. Both of these have been proposed as alternatives to Kripke semantics. It is shown how these models can be seen as representing bisimulation classes and bounded bisimulation classes of Kripke models respectively. In the two sections after that we show how bounded bisimulation can be characterized by certain fragments of infinitary modal logic and by Ehrenfeucht games. The last section contains some examples of results proven by different authors in different contexts and shows how they can be seen as closely related using the notions introduced in this paper.