In this lesson from Yale's Creating Change through Social Entrepreneurship course, students survey the range of revenue models available to social enterprises, from serving large volumes of low income customers at thin margins to blended models that combine earned revenue with philanthropic support. The lecture explains how different missions and customer bases call for different approaches to generating sustainable income. Following the course's earlier case study material, this lesson turns to the financial architecture that allows a social venture to sustain its impact over time, setting up later lessons on operational efficiency and financial planning.