 According to realists, universals exist as mind-independent entities. In transcendent realism, put forward by Plato, they exist even if uninstantiated and are thus “transcendent” or “ante res” (“before the things”). In immanent realism, defended by Aristotle in opposition to his master, they are “immanent” or “in rebus” (“in things”), as they exist only if instantiated by objects. Contemporary notable supporters are Russell (1912) for the former and Armstrong (1978a) for the latter (for recent takes on this old dispute see the essays by Loux, Van Inwagen, Lowe and Galluzzo in Galluzzo &amp; Loux 2015). Transcendentism is of course a less economical position and elicits epistemological worries regarding our capacity to grasp ante res universals. Nevertheless, such worries may be countered in various ways (cf. entry on  platonism in metaphysics, §5;  Bealer 1982: 19–20; 1998: §2; Linsky &amp; Zalta 1995), and uninstantiated properties may well have work to do, particularly in capturing the intuitive idea that there are unrealized possibilities and in dealing with cognitive content (see  §3).  A good summary of pro-transcendentist arguments and immanentist rejoinders is offered by Allen (2016: §2.3). See also Costa forthcoming for a new criticism of immanentism, based on the notion of grounding.