Dispositions and potentialities seem importantly similar. To talk about what something has the potential or disposition to do is to make a claim about a future possibilitythe "threats and promises" that fill the world (Goodman 1983, 41). In recent years, dispositions have been the subject of much conceptual analysis and metaphysical speculation. The inspiration for this essay is the hope that that work can shed some light on discussions of potentiality. I compare the concepts of disposition and potentiality, consider whether (...) accounts of these concepts are subject to similar difficulties, and whether having a disposition or a potentiality can depend on extrinsic factors. The concept of a disposition I am working with is drawn from the recent literature in metaphysics and philosophy of science that focuses on the analysis of dispositional concepts and their role in a broader ontology. The concept of a potentiality is drawn from the bioethics literature that focuses on the moral relevance of potentialities that subjects of medical decisions mayor may not possess. Some preliminary conclusions I draw are the following: I. Potentialities are dispositions; 2. Due to problematic cases, potentiality ascriptions, like disposition ascriptions, are not reducible to counterfactual statements; and 3. Like dispositions, some potentialities can be extrinsic. Here I do not aim to draw any conclusions about the moral relevance of potentialities but rather to outline conceptual and metaphysical options available to those who seek to employ this concept. However, to the extent that these options are relevant to answering moral questions, I am skeptical about the prospects of finding a value-neutral way to choose between them. I have tried to outline a number of options regarding the nature of potentialities for those who would like that notion to play some role in their theorizing in bioethics, or elsewhere. There still are a number of decisions to make about how to explicate the concept of potentiality that is most relevant for one's purposes. How should one flesh out the associated counterfactuals, regardless of whether they hope to reduce potentiality claims to counterfactual conditionals? How should one circumscribe the relevant possible circumstances of manifestation for a given potentiality? Are the circumstances necessary for the actualization of a given potentiality to be counted circumstances of possession or circumstances of manifestation? Is the kind of which something is potentially a member a natural kind or a class whose membership is determined by convention? My anticipation, and perhaps my worry, is that these questions do not have answers that can be determined independently from the conclusions about the moral relevance of potentiality that a given theorist aims to establish. (shrink)