The aim of this paper is to clarify the connection between types of firms and types of assumptions about the information structure. Building on the role of information structure, notions of the firm as an organisation have been put forward which suggest that the firm can assume an alternative (to the market) coordinating role in conditions of contractual incompleteness. A comparison (and opposition) between two recent approaches to the theory of the firm as an organisation seems to suggest that different notions of incomplete contracts imply substantial differences in terms of the meaning of a Pareto-efficiency improvement, of the role to assign to vertical integration, and of the determinants of the dimension of the firm.