Reciprocity is the basis of social relations. It permits a peaceful and free society in which people and rights are respected. The essence of families and communities, it also enables the working of markets and organisations, while correcting their main failures. Reciprocity is also a basis of politics, and it justifies social policies. Although the importance of reciprocity has been widely recognised in other social sciences, it has, until recently, been somewhat ignored in economic analysis. Over the past three decades, economic theorist and moral philosopher Serge-Christophe Kolm has been at the forefront of research into the economics of the deepest aspects of societies. In Reciprocity, he provides a unique in-depth analysis of the motives, conducts, and effects of reciprocal relationships. In doing this, he explains crucial functionings of society and its economy, and the ways in which they can be improved. This book should be read by economists, sociologists, philosophers, and anyone concerned with understanding the economy of social relationships and its far-reaching consequences.