The study of entrepreneurship and the study of economic organizing lack contact. In fact, the modern theory of the firm virtually ignores entrepreneurship, while the literature on entrepreneurship often sees little value in the economic theory of the firm. In contrast, we argue in this chapter that entrepreneurship theory and the theory of the firm can be usefully integrated, and that doing so would improve both bodies of theory. Adding the entrepreneur to the theory of the firm provides a dynamic view that the overly static analysis of firm organizing cannot support. Moreover, adding the firm to the study of the entrepreneur provides important clues to how we can understand entrepreneurship.