Abstract: Gary Becker and others have done important work to broaden the content of self interest, but have not departed from seeing rationality in terms of the exclusive pursuit of self-interest. One reason why committed behavior is important is that a person can have good reason to pursue objectives other than self interest maximization (no matter how broadly it is construed). Indeed, one can also follow rules of behavior that go beyond the pursuit of one's own goals, even if the goals include non-self-interested concerns. By living in a society, one develops possible reasons for considering other people's goals as well, which takes one beyond an exclusive concentration on one's own goals, not to mention the single-minded pursuit of one's own self interest. The recognition of other people's goals may be a part of rational thought. If rational behavior may depart from the relentless pursuit of one's own goals, commitment has to be important in a theory of rationality. Furthermore, seeing the role of commitment in human behavior can have explanatory importance in allowing us to understand behavior patterns that are hard to fit into the narrow format of contemporary rational choice theory. Commitment is, thus, important both for practical reason and for causal explanation.