This chapter embeds the Harrod multiplier-accelerator model of section “The Multiplier-Accelerator Growth Model of Harrod” into a general economic-dynamic system with the object of further analyzing stability properties of solutions (state variables, ratios) to Keynesian macro growth and cycle models. Historically, the chapter also serves as a historical background for the subsequent neoclassical growth models of Solow (Chap. 11 ). From a purely mathematical point of view, the aggregate demand-side growth models have essentially the same ratio and coordinate stability properties as dynamic supply side growth models of neoclassical kind. However, the latter has the economic potential for a proper general equilibrium model foundation.