ABSTRACT Locke bases his moral and political philosophy on his doctrine of the ‘law of nature’. Scholars have debated the content and grounding of this law and its relationship to Christian theology. The ambiguities of the Lockean natural law’s content are traceable to an unclear grammatical construction in a crucial passage of the Treatises of Government, which can be resolved by following out a related set of arguments in that work. The ambiguities of the Lockean natural law’s grounding can then be resolved by the hypothesis, strongly supported by textual evidence, that Locke relies tacitly on the reasoning of a parallel passage in Hobbes. Lockean natural law rests on neither atheistic nor specifically Christian premises but on a hypothetical natural theology. Locke’s conclusions from that natural theology represent an attempt to follow out Hobbesian logic while also tightening it up on one important point on which Hobbes himself appears to vacillate.