This paper focuses on the foundational role of interactive epistemology in the problem of generating plans for rational agents in multiagent settings. Interactive epistemology deals with the logic of knowledge and belief when there is more than one agent. In multiagent settings, we are interested in not only the agent’s knowledge of the state of the world, but also its belief over the other agents’ beliefs and their beliefs over others’. We adopt a probabilistic approach for formalizing the epistemology. This paper attempts to answer the question of why we should study the interactive epistemology of agents within the context of multiagent planning. In doing so, it motivates the need for a more detailed examination of the epistemological foundations of multiagent planning. We conclude this paper with a framework for multiagent planning that explicitly constructs and reasons with nested belief structures.