 Hawley and Bird (2011) argue that natural kinds are complex universals. A complex universal is a universal whose parts are universals (just as a complex particular is a particular whose parts are particulars). In the case of the electron the fundamental universals (the electron’s mass, charge, and spin) do combine to form a complex universal. Since an universal is wholly located where the universal is located, every entity that instantiates electronhood also instantiates its component universals, the electron’s mass, charge, and spin. Not every collection of universals constitutes a natural kind, just as not every collection of particulars constitutes a natural (complex) particular. The facts that explain the clustering of properties explain why these universals compose a complex one. Not every complex universal is, like electronhood, precise. Some are vague, and this fact can accommodate the indeterminacy of kind constitution implied by Boyd’s view of the clusters in the case of biological kinds.