The purpose of this thesis is to argue that the core of a monetary economy is a network of triangular contracts between banks, firms, workers and capital goods suppliers. Not only does this network give rise to the creation and valuation of money but it is the organising feature of modern economies, giving rise to both episodes of stability and crises. In constructing this argument I consider both orthodox and heterodox points of view. We analyse equilibrium models of money, and find that while money can exist in sequence economies with frictions, models of this type give no justification for its creation, valuation or holding for any significant duration, either theoretically or experimentally. Models that introduce dated goods and trading frictions to motivate the issue of risk-spreading ‘bundled’ debt are more promising for money creation, although they still cannot explain the the holding and valuation of money. Using the concept of team-production of Alchian and Demsetz and that of ‘hostage-taking’ in contracts owing to Williamson, we demonstrate how the issue of a token of generalised purchasing power from a team-production contract can enhance output and consumption. This conclusion motivates an original monetary theory of production that integrates the insights of Post-Keynesian monetary theory and the triangular contracts of the Circulation Approach and expresses them in a way that shows consistent asset and liability matching through a balance sheet approach. The creation and valuation of money and the determination of interest are embedded within the central processes of this economy. The features of the monetary production economy we analyse are in contrast to the mainstream proposition that the economy as a whole is rendered coherent by the existence of a unique and stable equilibrium determined by the utility-maximisation of households and the profit maximisation of firms. Apart from their inability to describe the economy in aggregate, such models treat money as an afterthought that is in no way core to their conception. We set the triangular contracts within a rigorous stock-flow framework of the type developed by Godley and Lavoie and argue that the shifting of the level of impact of uncertainty and failed expectations induced by money leads to specific patterns of economic disruption. These patterns are independent of the specific behavioural characteristics of households and firms and so are robust to policy changes that leave the institutions of the monetary production economy intact. We briefly assess current monetary policy and alternatives in the light of these findings.