The thesis of this essay is that social conventions of the kind Lewis modeled are generated and maintained by a form of practical reasoning which is essentially common. This thesis is defended indirectly by arguing for an interpretation of the role of salience in Lewis’s account of conventions. The remarkable ability of people to identify salient options and appreciate their practical significance in contexts of social interaction, it is argued, is best explained in terms of their exercise of what I (...) call “salience reasoning,” a form of common practical reasoning. The more widely accepted understanding of salience competence, the “natural salience” understanding, fails as an interpretation of the notion at work in Lewis and Schelling (on whom Lewis relied) and is inadequate as an explanation of salience competence. (shrink)