Locke's Essay Concerning Human Understanding is considered by many to be the locus classicus of a number of influential arguments for conventionalism, according to which there are no objective, privileged ways of classifying things in the natural world. In the dissertation I argue that Locke never meant to reject natural kinds. Still, the challenge is to explain how, within a metaphysics that explicitly denies mind-independent essences, we can make sense of a privileged, objective sorting of substances. I argue that we do so by looking to Locke's conception of God as divine architect of created substances.