John Locke discusses the notions of identity and diversity in Book 2, Chapter 27 of An Essay Concerning Human Understanding. At the beginning of this much-discussed chapter, Locke posits the place-time-kind principle. According to this principle, no two things of the same kind can be in the same place at the same time (2.27.1). Just what Locke means by this is unclear, however. So too is whether this principle causes problems for Locke, and whether these problems can be resolved. This is significant because the place-time-kind principle is foundational to Locke's discussion of identity. Moreover, the place-time-kind principle stands at the center of a number of lively and long-standing debates in Locke scholarship. These include the debates over the ontological status of Lockean persons, and whether Locke is a relative identity theorist, to name just two. In this paper, I offer a survey of how Locke's place-time-kind principle has been interpreted in the secondary literature. The aim of this taxonomy is to clarify where the differences between competing interpretations lie, and additionally show just how challenging it is to determine which reading is best.