Say that an entity makes true (or is a truthmaker for) a sentence or theory if the existence of that entity is, in some sense, sufficient for the truth of the sentence or theory. (It is left open for now just how to understand this notion of sufficiency.) In some cases, truthmakers are easy to come by. For example, the sentence ‘Socrates exists’ has Socrates as a truthmaker (assuming, at any rate, that Socrates has real existence; see §3.2 below). The sentence ‘Elephants exist’ has multiple truthmakers: each and every particular elephant (assuming elephants are necessarily elephants; see §3.3 below). Other cases are more problematic. Consider the conjunction: ‘Socrates exists and Plato exists’. Neither Socrates nor Plato, by himself, is a truthmaker for the conjunction; we need the pair of Socrates and Plato. But how should we understand ‘pair’ here? There are three options. If one is a universalist about mereological composition—for any things, there is a mereological sum composed of just those things—then perhaps the sum of Socrates and Plato can serve as a truthmaker for the conjunction. If one is a realist about sets—and sets exist “in the world” when their members do—then perhaps the set with Socrates and Plato as its members can serve as a truthmaker. But if we reject mereological universalism and set theoretic realism, then we will have to allow that the truthmaker relation takes a plural argument: Socrates and Plato together are truthmakers for the conjunction, but there is no single entity that is a truthmaker. In what follows, it will be simplest to speak as if, whenever a theory has truthmakers, it has a single entity as a truthmaker; but only minor emendations would be needed to allow for plural truthmaking.