Germany is one of the most important exporters of manufacturing goods in the world, but by far not all manufacturing firms in Germany are exporters, and there is a remarkable gap between the share of exporters in all manufacturing firms between West Germany and East Germany. While in West Germany in 2004 about two in three manufacturing plants were exporters, fourteen years after re-unification this share was less than fifty percent in the former communist East Germany. Given that exports play a key role in shaping business cycles and growth in Germany, and the much higher unemployment in East compared to West Germany, promotion of exports by East German firms figure prominently on the policy agenda. However, the reasons for the large difference in the propensity to export between East and West German firms are not yet well understood, not least due to a lack of comprehensive micro data. Using unique new data and a recently introduced non-linear decomposition technique this paper shows that the huge difference in the propensity to export between West and East German plants can only partly be explained by differences in firm size, productivity, and technology intensity.