ABSTRACT This study examines whether top management team (TMT) functional background diversity affects managerial forecasting capability. We find that TMTs with more diverse functional backgrounds issue more accurate earnings forecasts. Additional tests reveal that the negative association between TMT functional background diversity and management forecast errors becomes weaker when TMTs work together for a long time, when subgroups are more likely to develop within the team, when CEOs are more powerful, and when team size is larger. By contrast, the reduction in management forecast errors is more significant for functionally diverse TMTs when forecasting difficulty is higher. These findings suggest that TMT functional background diversity plays an important role in managerial forecasting capability. Data Availability: Data are available from the sources cited in the text. JEL Classifications: M14; M41.