When a bank or a credit union turns you down for a loan because your debt-to-income ratio is too high, can you turn to total strangers to get the money? Yes, you can, and we are not talking about criminal acts. It\u27s called peer-to-peer (P2P) lending or social lending. Prosper was the first company to take the vision of social lending and convert it into practice on the Internet in the United States, and it enjoyed fast growth after launch. Four years later, however, it is facing old and new challenges, and its survival is on the line. This case depicts the opportunities and pressures Prosper faced, its actions and reactions, and its future. Prosper has made and will make many important decisions, and Prosper’s successes and challenges are rich material to study