A theory of leadership is proposed and tested. Leaders perform many roles in a firm. They become leaders because they succeed at these tasks more than others and at least some of their successes are visible. The theory implies that leaders tend to be more able, place themselves in visible decision making situations more frequently and are generalists. Also, the most able leaders should be found in the highest variance industries, where decision making has the greatest payoff. The theory is tested using data on Stanford alumni and is confirmed. Leaders are generalists rather than specialists, both innately and in their pattern of skill acquisition.
