Leadership often serves as an explanatory category for performance outcomes (i.e., failure and success). This process can strengthen or weaken leadership effectiveness, because contingent on their performance leaders may gain or lose follower endorsement - the basis of leadership. Drawing on the social identity analysis of leadership, we hypothesized that leader group prototypicality and performance information interact to predict followers' perceptions of leadership effectiveness. Because group prototypical leaders are more trusted by their followers, we hypothesized that group prototypical leaders are evaluated as more effective after failure information than non-prototypical leaders. In contrast, we predicted that both prototypical and non-prototypical leaders should receive similar evaluations of leadership effectiveness after success. We found support for our predictions in a scenario experiment, a cross-sectional field study, and a laboratory experiment. © 2009 Elsevier Inc. All rights reserved.