This volume is a debate about a sociology and economics of money: a form of positive trespassing. It is unique in being written by scholars of both disciplines committed to this mutual venture and in starting from the original groundwork laid by Geoffrey Ingham. The contributors look critically at money's institutions and the meanings and history of money-creation and show the cross cutting purposes or incommensurable sides of money and its crises. These arise from severe tensions and social conflicts about the production of money and its many purposes. We demonstrate the centrality of money to capitalism and consider social disorders since the 2007 crisis, which marks the timeliness and need for dialogue. Both disciplines have far too much to offer to remain in the former, damaging standoff. While we are thankful to see a possible diminution of this split, remnants are maintained by mainstream economic and sociological theorists who, after all the crises of the past 30 years, and many before, still hold to an argument that money really does not 'matter'. We suggest, to many different and interested audiences, that since money is a promise, understanding this social relation must be a joint though plural task between economics and sociology at the very least.