This essay is about the character and structure of the natural rights theorizing which grounds – or at least seeks to ground – natural rights that strongly support libertarian conclusions. It focuses entirely on this first phase of natural rights argumentation. It is not concerned with the ways in which libertarian-minded natural rights thinkers employ or refine their affirmations of natural rights to support downstream conclusions about, e.g., what property rights and contractual rights individuals have and how those rights are acquired, or why there must be radical limits on the use of coercive power by the state (or state-like entities), or under what special circumstances, if any, an individual or a state may act toward other individuals in ways that would normally be forbidden by the rights of those individuals. The key contention of this essay is that the grounding argument for natural rights has a basic abiding structure. I support this contention in two ways. First, I offer a highly stylized statement of this argument that connects the types of consideration that are common within grounding arguments for libertarian-friendly natural rights in a philosophically promising way. Second, I show that this basic structure – of course, with some local variations – is to be found in the foundational arguments of prominent natural rights theorists. I survey arguments offered by Hugo Grotius (1583–1645), John Locke (1632–1704), Lysander Spooner (1808–1887), Ayn Rand (1905–1982), and Robert Nozick (1938–2002).