Theorizing on procedural justice has assumed that people's reactions to outgroup authorities are to a large extent based on instrumental concerns. Therefore, attention is primarily directed to outcomes rather than procedures in encounters with outgroup authorities. In the current article we propose that in order for people dealing with outgroup authorities to be strongly affected by procedural fairness, the available outcome information should be ambiguous. Furthermore, we argue that people confronted with an outgroup authority react particularly negatively to unfair procedures that give them negative outcome expectancies. These patterns are not expected in encounters with ingroup authorities. Two experiments support our line of reasoning. The discussion focuses on the implications of these findings for the integration of theoretical perspectives on procedural justice. Copyright © 2004 John Wiley & Sons, Ltd.