The book: Tribal Leadership: Leveraging Natural Groups to Build a Thriving Organization. Collins; February 2008.

The big idea: A company's culture, whether it is collegial or borderline feral, is determined by the quality of its "tribes." Tribes are groups of 20 to 150 workers who are unified by attitudes, values, and goals. The book identifies five stages of tribal life and suggests ways to get better results from individual members and entire tribes.

The backstory: Authors Dave Logan, John King, and Halee Fischer-Wright are partners at CultureSync, a Los Angeles management consulting firm. They analyze performance as -a product of culture. It's territory that has been fruitfully mined by authors like John Kotter and Edgar Schein. Tribal Leadership's chief contribution is that it studies cultures as they develop in smaller, naturally occurring units. Large corporations don't necessarily have monolithic cultures, the authors observe, but rather are the products of many tribal cultures rubbing together. Small companies--for good or ill--are often tribes unto themselves. They are highly cohesive but run the risk of insularity.

Intriguing idea: The book takes an unusually nuanced view of high-performance cultures, identifying three kinds that range from Wild West individualism to near utopias in which competitors cease to matter and a noble cause "is the group's only compass."

Pass-along value: Figure out a subtle way to share the book with your Type A's and prima donnas, as it expertly describes the tension between loners who perform exceptionally and those who perform exceptionally but who measure success as part of a team.

Things you didn't know were bad for you: Meetings with only one other person (because talking to one person at a time is inefficient and increases the possibility that your communications are inconsistent from one person to the next) and self-help books (which often cheer on the individual and ignore the tribe)

Rigor rating: 8 (1=Who Moved My Cheese?; 10=Good to Great). The authors interviewed 24,000 people over eight years.

Readability rating: 6 (1=Who Moved My Cheese?; 10=Academy of Management Journal). The authors come off as eggheads in mass-market drag.

If you read nothing else: Skip right to Chapter Eight ("Establishing Tribal Leadership"). It will appeal to early-stage companies trying to get culture right from the get-go.