If your company is intrigued by the opportunities at the bottom of the pyramid but hesitant to plunge in, it’s not alone: Despite the extent of the markets and the volume of the hype, few multinational firms have built sizable businesses serving people who survive on just a few dollars a day. Companies sense that profits in this market are elusive, and the evidence backs them up.

A version of this article appeared in the March 2011 issue of Harvard Business Review.