Prior research on corporations finds that there exists a large unexplained firm-specific heterogeneity in corporate behaviors stemming from the effects of managers. This research identifies managerial personalities and tests their effects on corporate behaviors both experimentally and empirically. First, the effects of managerial personalities on corporate financing decisions are tested using a laboratory experiment with managers in South Korea. The laboratory experimental market is à la Modigliani and Miller but with two frictions, bankruptcy costs and corporate taxation. Leverage choices of managers with particular personality traits are compared against the optimal capital structure computed from the static trade-off theory. The results ...