People may conceptualize certain categories as held together by a category-specific “essence”—some unobservable, critical feature that causes the external features of a category to emerge. But what is the nature of this essence? Recently, Rose and Nichols have argued that something's essence is fundamentally its telos or purpose. However, Neufeld has challenged this work on theoretical grounds, arguing that these effects arise only because people infer an underlying internal change when reasoning about a change in telos. In Neufeld's view, it (...) is the underlying internal cause, and not the telos itself, that serves as an essence (consistent with classic views of scientific essentialism). Here, we ask: Is teleology the primary force behind psychological essentialism? We begin by successfully replicating Rose and Nichols’ key findings in support of teleological essentialism. In two further experiments, however, we demonstrate that teleology may not be the central way that people understand the essences of living things. We show that internal changes matter at least as much as changes in teleology. These findings suggest that while teleology may be one important cue to category membership and the essences of living things, it may be premature to say that we are “teleologically essentialist.”. (shrink)