in studying dozens of companies over many years, we have found that those with skill at simultaneously building private and public value tend to have a nuanced understanding of their constituencies. the 4 billion people at the base of the pyramid whose output represents one-third of the world's economy are not a monolith. to emulate the most effective pioneers, companies must commit to learning what constitutes value for the various components of this population. the way to start is to divide the 4 billion people into three basic segments.