The attributions that are made for subordinates' work performance have important implications for supervisors, subordinates, and the organization as a whole. However, cognitive biases, such as the self-serving or the actor-observer biases, can influence whether positive or negative attributions are made. We anticipated that subordinates whose relationship with their supervisor was positive would be more likely to experience positive attributions for their performance through the self-serving bias, whereas subordinates with a poorer supervisor relationship would experience negative attributions for their performance through the actor-observer bias. Results of a study of this prediction did show asymmetries in the attributions for performance based on in-or outgroup status, with in-group supervisors, in-group subordinates and out-group subordinates all displaying the self-serving bias in their attributions for subordinate performance, and with supervisors displaying the actor-observer bias toward out-group subordinates. This may cause out-group members to become alienated from the organization, resulting in lowered job performance and increased turnover. As a result, organizational homogeneity may increase, leading to less diversity of perspectives within the organization.