The belief that teams make us more creative and productive--and are the best way to get things done--is deeply entrenched. But Hackman, a professor of organizational psychology at Harvard and a leading expert on teams, is having none of it. Research, he says, consistently shows that teams underperform despite all their extra resources. In an interview with senior editor Diane Coutu, Hackman explains where teams go wrong. Shockingly, most of the time members don't agree on what the team is supposed to be doing or even on who is on the team. The belief that bigger is better also compounds problems; as a team grows, the effort needed to manage links between members increases almost exponentially. Leaders need to be ruthless about defining teams and keeping them small (fewer than 10 members), and some individuals (like team destroyers) should simply be forced off. The leader also must set a compelling direction for the team--but in so doing, may encounter intense resistance that puts him or her at great risk. Hackman explores other fallacies about teams--for instance, that teams whose members have been together a long time become stale. In fact, research reveals that new teams make 50% more mistakes than established teams. To avoid complacency, though, every team needs a deviant--someone who is willing to make waves and open up the group to more ideas. Unfortunately, such individuals often get thrown off the team, robbing it of its chance to be magical. Leaders can't make a team do well. However, by being disciplined about how a team is set up and managed, instituting the right support systems, and providing coaching in group processes, they can increase the likelihood that a team will be great.