This classic article shows how to make mass customization and efficient and personal marketing work by putting the producer and consumer in a “learning relationship.” Over time, this ongoing relationship allows your company to meet a customer's changing needs over time. Furthermore, as your company develops learning relationships with its customers, it should be able to retain their business virtually forever. Since 1922, Harvard Business Review has been a leading source of breakthrough management ideas-many of which still speak to and influence us today. The Harvard Business Review Classics series now offers readers the opportunity to make these seminal pieces a part of your permanent management library. Each highly readable volume contains a groundbreaking idea that continues to shape best practices and inspire countless managers around the world-and will have a direct impact on you today and for years to come.