Transactions often differ on important dimensions from spot exchanges on perfect neo-classical markets. Information is seldom complete and instantaneous exchange is just as rare as full competition. The authors in this volume extend the standard economic model stressing the proposition that the social context is an important determinant of the governance of transactions. To foster the development of a body of cumulative knowledge in the new economic sociology, this approach is consistently applied to a diversity of topics including purchase relations, strategic alliances, and relations among lawyers and clients as well as employers and employees. This volume is divided in three parts. The first part offers surveys of purposive behavior models in research on governance as well as theoretical work extending these models. The contributions in the second and third part all have an empirical component and deal with governance in the various phases of exchange relations; search and selection, negotiating and contracting, contract execution and performance, and conflict regulation. The second part focuses on governance in markets, while the third part discusses governance in organizations.