Moral identity affects interpersonal relationships by guiding how people perceive and respond to feedback, evaluate others and select task partners and friends. Self-described principled participants (high scorers on the Integrity Scale) more strongly preferred principled-prototypic others over expedient ones and believed it possible to be more principled in one's beliefs (Study 1), preferred evaluators who regarded them as principled over expedient (Study 2), had friends who saw them as principled and paired up with friends who were themselves principled (Study 3). In contrast, expedient individuals did not display mirror-image reactions but saw merit in being both expedient and principled; they were accepting of any relevant feedback and partner preferences. Moral identity is a key link between ethical beliefs and behaviours. Copyright © 2010 John Wiley & Sons, Ltd.