To many, the phrase “family business” connotes a small or midsized company with a local focus and a familiar set of problems, such as squabbles over succession. While plenty of mom-and-pop firms certainly fit that description, it doesn’t reflect the powerful role that family-controlled enterprises play in the world economy. Not only do they include sprawling corporations such as Walmart, Samsung, Tata Group, and Porsche, but they account for more than 30% of all companies with sales in excess of $1 billion, according to the Boston Consulting Group’s analysis.

A version of this article appeared in the November 2012 issue of Harvard Business Review.