How do states come to select norms? I contend that, given a number of conditions are present, states select norms in three ideal-typical stages: innovative argumentation, persuasive argumentation, and compromise. This norm selection mechanism departs from the existing literature in two important ways. First, my research elaborates on the literature on advocacy networks. I explain why agents engage in an advocacy for a normative idea in the first place; I add the epistemic dimension of reasoning to argumentation theory; and I show in detail the pathways through which persuasive argumentation links an advocated idea and already-established sets of meaning. Second, synthesizing rationalist and constructivist selection mechanisms, I contend that successful argumentation makes recalcitrant actors eager to reach a compromise with the advocates as long as this does not violate their most cherished beliefs. The Republic of Ireland’s eventual selection of the territorial status quo norm in the late 1990s lends empirical evidence to this norm selection mechanism.