For nearly two decades, education entrepreneurs have been working to transform the K-12 public education system in the United States. "Social entrepreneurship" has become part of the language of a new generation of idealists, many of whom are focused on education. The nineteen cases in this book profile entrepreneurs who are pursuing opportunities to create pattern-breaking social change in our public schools--in particular, by creating high-quality educational opportunities for low-income and minority students who are dramatically underserved by the current public education system. Based on a popular course developed and taught at the Harvard Business School, this casebook is organized into four modules: (1) Understanding the Context of Urban Schooling in the United States; (2) Tackling the "People Problem"; (3) Focusing on Performance; and (4) Launching and Growing New Schools. Students are invited to explore four overarching questions: Why are there opportunities for entrepreneurs in a sector that is funded with public dollars and delivered by public agencies? Why is entrepreneurial activity aggregating around certain opportunities? What are the possibilities and constraints faced by entrepreneurs in each opportunity area? How can we evaluate the impact of these entrepreneurs' efforts?