The American economy has traditionally been divided into three sectors: government, for-profit businesses and non-profit charities. In more recent years, students of American business have begun talking about a fourth category, often called the "for-benefit" sector. Fitting in between traditional businesses and charitable groups, for-benefit organizations are moneymaking enterprises with a social agenda. As Mike Osborne reports, American universities are beginning to recognize this fourth sector of the economy, and to prepare students to enter it.