In this dissertation I examine the emergent phenomenon of social entrepreneurship through the lens of the structure of entrepreneurial payoffs under conditions of near-Knightian uncertainty. Current theory assumes entrepreneurs will respond to a new form of incentive, beyond the pursuits of wealth, power, and prestige. It also assumes that productive entrepreneurship can result from a shift in the structure of payoffs. I examine four for-profit social entrepreneurial experiments executed in Southern Africa in order to enhance understanding of the question: "What recurring challenges do for-profit social entrepreneurs face in attempting to restructure payoffs under conditions of near-Knightian uncertainty?" My data are drawn from field observations, company archival records, email communications, and unique targeted interventions designed to solve vexing challenges which arose in the course of the experiments. The dissertation makes several contributions. First, it uncovers several new insights from my findings which should inform future research in for-profit social enterprises. Second, it sheds light on enterprise creation under conditions of near-Knightian uncertainty. Third, it introduces a framework for understanding the challenges faced by nonsingular objective firms, and proposes that lack of success in the creation of such firms is not necessarily failure – there are multiple levels of success that are part of an Aspirations Cascade, the highest efficiency being delivered by the social impact enterprise and the lowest efficiency achieved from direct charity.