This paper reconstructs the conceptual foundations of Locke’s unilateralist theory of original appropriation through a critical comparison with the rival compact theories of Grotius and Pufendorf. Much of the normative and conceptual framework of Locke’s theory is common to theirs. Integrating his innovative doctrines on labour and natural self-proprietorship into this received theoretical framework logically required Locke to make several conceptual amendments. I highlight three all but overlooked revisions: (i) an unusually broad conception of labour; (ii) a reduction of mere (...) use-rights to property rights; and (iii) a novel non-self-preservationist interpretation of the divine authorization to use natural resources in common. The reconceptualization of ‘labour’ is theoretically the most fundamental, underpinning the other two. My contextual reconstruction enhances our grasp of the structure of Locke’s theory of original appropriation. It also reveals Locke’s main objection to compact theories to be an external one, hinging on idiosyncratic conceptualizations of key notions. (shrink)