Incentives are typically conceived as a form of trade, and so voluntariness appears to be the only ethical concern. As a consequence, incentives are often considered ethically superior to regulations because they are voluntary rather than coercive. But incentives can also be viewed as one way to get others to do what they otherwise would not; that is, as a form of power. When incentives are viewed in this light, many ethical questions arise in addition to voluntariness: What are the (...) responsibilities of the powerful in using incentives? Can incentives be manipulative or exploitative, even if people are free to refuse them? Like all other forms of power, incentives can be abused. This paper develops criteria for distinguishing their legitimate from their illegitimate uses, viz. legitimacy of purpose, voluntariness, and effect on character. The criteria are then applied to three cases: plea bargaining, recruiting medical research subjects, and motivating children to learn. Thinking of incentives in terms of.. (shrink)