This paper examines the relationship between trade and growth through the learning-by-exporting mechanism. According to the hypothesis underlying this mechanism, the more a country exports, productivity also increases, which leads to higher rates of growth of the output. A theoretical model supporting this hypothesis is offered here by adapting the Ramsey-Cass-Koopmans model to an open economy where per capita exports are used as the transmission channel of technology. Empirical evidence supporting this mechanism in a wide sample of developing countries is also presented here by means of a panel data model.