This paper presents Sen's theory of agency, focusing on the role of commitment in this theory as both problematic and potentially illuminating. His account of some commitments as goal-displacing gives rise to a dilemma given the standard philosophical theory of agency.Eithercommitment-motivated actions are externally motivated, in which case they are not expressions of agency,orsuch actions are internally motivated, in which case the commitment is not goal-displacing. I resolve this dilemma and accommodate his view of commitment as motivation by developing a (...) broader descriptive theory of agency, which recognizes both agent goal-directed and goal-displacing commitments. I propose a type of goal-displacing commitment, which I call ‘tacit commitment’, that can be seen to fit between the horns. Tacit commitments regulate behaviour without being made conscious and explicit. This resolution suggests a means of bridging the normative/descriptive gap in social-scientific explanation. (shrink)