This study examined the complementary role categorization and attribution processes play in managers’interpretations of event causes. Categorization theory suggests that events with distinctive internal or external causes should be interpreted, respectively, as internal and external. Attribution theory and research on self-serving attributions, on the other hand, suggest that events with positive outcomes should be attributed to internal causes and events with negative outcomes to external causes. Study results showed a very significant interaction between distinctiveness of event causes (internal-external) and the valence of event outcomes (positive-negative). This interaction suggests that managers use categorization processes to interpret positive events, but more effortful attributional processes to interpret events with negative outcomes. There also was evidence of self-serving attributional biases in managers’interpretations of event causes, especially events with equivocal causes. Study findings appear to be unaffected by managerial position or background. We discuss the contribution this study makes to extant research and its implications for future research.