Currently more and more large, vertically integrated firms are being transformed into flatter organisations that encompass decentralised decision structures. The author argues that an understanding of this new type of firm, called market-like firm, is missing from the theory of the firm (transaction cost theory), for two reasons. On the one hand, the Williamsonian framework of governance structures does not explore the distinguishing mark of the firm, and, on the other hand, it cannot explain the variety of firms. To overcome these shortcomings, the author proposes the extension of the Williamsonian framework with the concept of “firm-ness” that is based on the distinction between ideal-type and real-type.