A growing body of empirical work has documented the superior performance characteris- tics of exporting plants and firms relative to non-exporters. Employment, shipments, wages, productivity and capital intensity are all higher at exporters at any given moment. This paper asks whether good firms become exporters or whether exporting improves firm performance. The evidence is quite clear on one point: good firms become exporters, both growth rates and levels of success measures are higher ex-ante for exporters. The benefits of exporting for the firm are less clear. Employment growth and the probability of survival are both higher for exporters; however, productivity and wage growth is not superior, particularly over longer horizons.