We propose a theory of corporate social responsibility (CSR) by linking it to a firm’s product market. In our model, the firm’s product exhibits network effects whereby its value increases with the number of consumers who purchase it. Moreover, with advancements in technology and big data, the firm can adopt personalized pricing for each consumer. We show that such a firm could use CSR as a commitment device for low product prices, which helps overcome the coordination problem among consumers and increases firm profits, thus supporting the notion of “doing well by doing good.”