The current study examines the role of ethical cognition as a psychological mechanism linking ethical leadership to employee engagement in specific discretionary workplace behaviors. Hypotheses are developed proposing that ethical leadership is associated with employees’ negative moral equity judgments of workplace deviance (a discretionary antisocial behavior) and positive moral equity judgments of organizational citizenship (a discretionary prosocial behavior). In addition, hypotheses propose that moral equity judgments are a key type of ethical cognition linking ethical leadership with employee behaviors. Hypotheses are tested in a cross-organizational sample of 190 supervisor–employee dyads. Results indicate that employees who work for ethical leaders tended to judge acts of workplace deviance as morally inequitable and acts of organizational citizenship as morally equitable. In turn, these judgments guided employee regulation of behavior, and mediated the relationships between ethical leadership and employee avoidance of antisocial conduct and engagement in prosocial behavior.