If acting morally can be viewed as acting consistently with a moral principle or rule, then being a person with moral integrity can be viewed as consistently applying moral principles or rules across different types of situations. We advance a view of moral integrity that incorporates three distinct, but interrelated, types of moral consistency: cognitive, emotional and motivational moral consistency. Our approach is based on Self-Determination Theory, a motivational theory that can explain when a moral rule becomes the primary motive for behavior. We argue that moral integrity is achieved when a person acts on the basis of an internal moral system of principles, emotions and motives and provide an account of the way that it develops during a person's interaction with the environment.