The book: It's Not What You Sell, It's What You Stand For: Why Every Extraordinary Business Is Driven by Purpose, by Roy M. Spence Jr. with Haley Rushing; Portfolio; February 2009.

The big idea: The title screams social responsibility, but this book offers mostly pragmatic advice. The big idea is that every business needs a big idea. A company's "passion" guides decision making and defines brand. Don't ask what makes your business different. Ask, rather, what difference your business makes.

The backstory: Spence and Rushing are, respectively, CEO and senior vice president of GSD&M Idea City in Austin. They have advised some of the world's best brands, including BMW and Wal-Mart.

If you read nothing else: Chapters Seven and Eight provide the book's key insight: Once you understand what your company stands for, you can embody it. That may sound like pap but is almost magical when realized in CEOs such as Barry Feld of World Market and Herb Kelleher of Southwest Airlines. The Southwest story unfolds with the immediacy of time-lapse photography, making even this well-known icon feel fresh.

Cognitive dissonance alert: The authors write extensively and engagingly about Wal-Mart, a longtime client. But they jig around the company's controversial treatment of employees.

Rigor rating: 7 (1=Who Moved My Cheese?; 10=Good to Great). The lessons derive chiefly from GSD&M's client base, so the research is deep but not broad.