The success or failure of top management may hinge on something few of us ever consider. That is the range of temperaments across the senior team. Team composition has been sliced and diced across every conceivable dimension of age, sex, race, national origin, tenure and function, but it turns out that one important contributor to team success is something altogether different: a common attitude toward life.Recent research appearing in Administrative Science Quarterly convincingly demonstrates that teams sharing the same level of “positive affect” (disposition) work together better. In fact, companies that had top teams made up of people with similar temperaments enjoyed 4% to 6% higher market-adjusted earnings per share than companies that did not. The study included 301 top executives at 62 major U.S. organizations, selected from among the Fortune 500, the 100 largest privately held companies, leading nonprofits and a few newsworthy emerging growth companies.The researchers surveyed the executives' levels of enthusiasm, mental alertness, energy and determination.