Boards of directors typically believe that transforming a company from merely good to truly great requires a larger-than-life personality--an egocentric chief to lead the corporate charge. Think "Chainsaw" Al Dunlap or Lee Iacocca. In fact, that's not the case, says author and leadership expert Jim Collins. The essential ingredient for taking a company to greatness is having a "Level 5" leader at the helm--an executive in whom extreme personal humility blends paradoxically with intense professional will. Collins paints a compelling and counter-intuitive portrait of the skills and personality traits necessary for effective leadership. He identifies the characteristics common to Level 5 leaders: humility, will, ferocious resolve, and the tendency to give credit to others while assigning blame to themselves. Collins fleshes out his Level 5 theory by telling colorful tales about 11 such leaders from recent business history. He contrasts the turnaround successes of outwardly humble, even shy, executives like Gillette's Colman M. Mockler and Kimberly-Clark's Darwin E. Smith with those of larger-than-life business leaders like Dunlap and Iacocca, who courted personal celebrity. The jury is still out on how to cultivate Level 5 leaders and whether it's even possible to do so, Collins admits. Some leaders have the Level 5 seed within; some don't. But Collins suggests using the findings from his research to strive for Level 5--for instance, getting the right people on board and creating a culture of discipline. "Our own lives and all that we touch will be better for the effort," he concludes.