Holistic views of content claim that we each speak and think in distinct and idiosyncratic idiolects: although we may often entertain thoughts with similar contents, the content of our thoughts can never be type-identical. Many authors find this feature of holism problematic. Denying that two subjects can share thought content seems to lead to difficulties when it comes to providing accounts of various intersubjective phenomena, such as communication and disagreement. A common holist response is to claim that explanations of these phenomena should appeal to conceptual similarity rather than shared content. To make this approach plausible, holists must provide an account of what it is for two concepts to be similar. Fodor and Leporeargue that this cannot be done: accounts of conceptual similarity (across non-identical networks) must presuppose a robust notion of conceptual identity, and this is inconsistent with the holist’s view. In this paper, I provide an account of conceptual similarity for theories of content that are both fully holistic and purely internalist. I argue that similarities between the perceptual representations that are connected to holistic networks can be used to ground comparisons of conceptual similarity without appeal to either robust conceptual identity or the external world.