It is always easier to recognize a problem like this one and propose a solution when someone else has stumbled across it first. For instance, a company store in a factory town with no other retail within a ten-mile radius. For instance, a regional airport that’s only served by a single airline. This problem is resolved here by defining monopoly power in terms of substitution and identifying it as one of several determinants of the markup. Monopolies can be identified by the following characteristics: A lack of competition within a market. Kriesler (1987), for example, noted that Kalecki created considerable confusion by failing to clearly distinguish between the degree of monopoly and the markup. Before turning to the theory it is important to point out that I have benefited as much from the mistakes of my predecessors as from their genuine insights. An unregulated monopoly has market power and can influence prices. Also in this theory, the relationships between monopoly power, demand elasticities, markups, total profits, and the distribution of profits, are traced systematically. Monopoly A monopoly is a firm who is the sole seller of itsproduct, and where there are no close substitutes. In this way, monopoly power is recognized as a fundamental characteristic of a firm which in turn affects other aspects of its behavior. First, monopoly power is defined formally in terms of substitution. It builds on the heritage of Post Keynesian authors, Robinson, Kaldor, and Kalecki, but literally extends the theory in several directions. The purpose of this paper is to outline a consistent microeconomic theory of the firm based on the concept of monopoly power. Explorations in Theory and Empirical Analysis.Immigration, Ethnicity, and Social Structure.Levy Institute Measure of Time and Income Poverty.Levy Institute Measure of Economic Well-Being.Monetary Policy and Financial Structure.The State of the US and World Economies.