What do you think causes millions of people to miss work and school in developing economies? Illness? Lack of childcare? Minimal professional training? Insufficient infrastructure? While all of those certainly play a role, I’m guessing that what Elizabeth Scharpf stumbled across as a critical factor in absenteeism wasn’t on your radar. While interning in Mozambique in 2005 for the one-person (!) private-sector development division of the World Bank — studying how small and medium-sized businesses can play a role in developing economies — Scharpf, now a 34 year-old graduate of Harvard’s graduate schools of business and government, happened to overhear a local colleague complaining that her employees often missed work because they were menstruating. Seriously? Perplexed and intrigued, Scharpf thought this might represent a business opportunity, and decided to dig deeper.