In this wide-ranging collection of essays, distinguished philosopher Margaret Gilbert investigates the structure of our social world. People often speak of what we do, think, and feel, and of our values, conventions, and laws. Asking what we mean by such talk, Gilbert invokes the foundational idea of joint commitment. She applies this idea to topics ranging from the mutual recognition of two people to the unity of the European Union, from marital love to patriotism, from promissory obligation to the rights of those who issue authoritative commands. Written clearly and without undue technicality, this richly textured collection of essays makes a powerful argument for the importance of joint commitment in our personal and public lives.