Everybody uses money every day, but we rarely stop to think about how money works. In this book, scholars from different disciplines seek to answer that question; from historians to economists, sociologists, a philosopher and a physicist. Money works as a social construction because we have mutual expectations that support its use - despite the seeming irrationality of trading valuable things or doing strenuous work for pieces of paper or numbers in accounts. Recently, there has been a revival of interest in monetary theory, not least because the impacts of globalizing markets and of new communication and information technologies have changed the forms of money. The deep crisis of the financial system has demonstrated the importance of a functioning monetary system and although renewed interest in this has led to significant contributions in various fields, it remains true that no social science discipline on its own is sufficiently equipped to explain the basic workings of monetary systems, their rapid innovation and their effects on social, economic and political structures. The contributors to this book report on their latest research on the origins of money, on the nature of monetary transactions, on money and the state, and on the role of money and finance in the recent global crisis. They show how established theories of money and the policies guided by these theories went wrong. This collection will be a valuable resource for students and researchers seeking a deeper understanding of money.