This paper analyses the relationship between firm productivity and export behavior in German manufacturing firms. We examine whether productivity increases the probability of exporting, and assert that there is a causal relationship from high productivity to entering foreign markets, as postulated by the recent literature on international trade with heterogeneous firms. In estimating productivity, we control for a possible simultaneity bias by using semiparametric estimation techniques. Moreover, we apply a matching technique in order to analyze whether the presence in international markets enabled firms to achieve further productivity improvements, without finding significant evidence for this. We conclude that high-productivity firms self...