Are social structures products of human action, expressions of individual or group power? Or are they essentially external constraints on human action, necessarily analyzed at a different level? How are themes of power and constraint to be joined in a common analytic approach? These have long been central questions for sociologists. since the collapse of functionalism as a unifying paradigm, however they have often appeared as the basis for sharp divisions between competing analytic paradigms. The divide between structuralism and rational-choice theory has been one of the most prominent such splits. Yet each approach has undergone a revival in past years. The editors of this book, in honour of Peter Blau, brought together a wide range of distinguished sociologists who have taken positions on different sides of this issue and brings them into focus as parts of a common discourse on the place of social structure and concepts of strategic action in sociological explanation.