A survey of some elementary macroeconomic models is presented which indicates the potential that exists for the application of control theory in economics. An initial linear model is developed systematically to embrace an increasing degree of economic sophistication leading to a non-linear formulation, the need for which is soon made apparent. Examples are given to demonstrate the use of characteristic root analysis, of the root locus technique to examine parameter sensitivity and of phase plane and stability concepts. At the same time, important economic interpretations which can be drawn from the results are indicated.