The, for economists well-known Goodwin model was one of the first models which tried to combine cyclical behavior and economic growth. The basis for this is the predator-prey model – a basic structure for every System Dynamicists. The economic literature about the Goodwin model is enormous, but so far, it was mostly concentrate on the mathematical behavior or on some extensions that could be implemented. In addition, there are only two papers from R. Solow and D. Harvie about an econometrical verification of the model and none from a System Dynamics’ perspective. This article provides therefore two System Dynamics models of Goodwin’s theory and tests the enhanced one on the German economic situation and on the data provide by Harvie 2000. Additionally there are some suggested modifications of the Goodwin model, tested from different authors, which reveal surprising outcomes for the understanding of Goodwin’s theory.