To promise someone to do something is to commit oneself to that person to do that thing, but what does that commitment consist of? Some think a promissory commitment is an obligation to do what’s promised, and that while promising practices facilitate the creation of promissory obligations, they are not essential to them. I favor the broadly Humean view in which, when it comes to promises (and so promissory obligations), practices are of the essence. I propose the Practice Reason Account (...) of promises, according to which a promise is basically to give oneself a self-interested practice reason to do what’s promised. One achieves this feat by invoking self-enforcing independent practice rules thanks to which one’s doing what’s promised preserves one’s promissory trust(worthiness) and promising power. However, nothing in this account supports the Hume-Rawls claim that promise-keeping or promise-breaking is right just when and because it conforms to practice rules that are justified by their good- or right-making properties. (shrink)