This article summarizes and assesses the growing body of empirical research in transaction cost economics (TCE). Originally an explanation for the scale and scope of the firm, TCE is now used to study a variety of economic relationships, ranging from vertical and lateral integration to transfer pricing, corporate finance, marketing, the organization of work, long-term commercial contracting, franchising, regulation, the multinational corporation, company towns, and many other contractual relationships. The main insights and predictions of TCE-in particular, the importance of governing transactions-are becoming increasingly accepted. The empirical support for these claims, however, is much less known. We believe the empirical literature, on the whole, is remarkably consistent with the predictions of TCE-more so than is typically the case in economics. After presenting an overview of the theory and a discussion of some theoretical and methodological preliminaries, we summarize the major findings and discuss their implications, particularly the potential applications to public policy. In an appendix we provide a more comprehensive list of articles, arranged by type of study, as a reference aid for researchers.