["The American Journal of Economics and Sociology, EarlyView. ", "\nABSTRACT\nWe consider theories of interest as they relate to what we will call the Gesell‐Keynes (GK) theory which is essentially a real theory of capital accumulation with a monetary constraint that arises because of a liquidity return on holding money. We give brief presentations of the neoclassical theory (Fisher), growth models (Solow and Ramsey), and monetary models of growth (Tobin and Sidrauski). The GK theory is a neoclassical theory of the return on capital with a liquidity return on money hindering the path to the growth theory steady state. The monetary growth models do address the GK liquidity return on holding money, and we will highlight a contrast here between how Gesell and Keynes relate to these with different models of the economy and their different solutions to the monetary constraint.\n"]