This paper develops a model of trade that features heterogeneous firms, technology choice and different types of skilled labor in a general equilibrium framework to explain within-industry increase in the relative demand for skilled workers. Its main contribution is to investigate the impact of firms' export and technology choice decisions on skill upgrading. Only firms in the upper range of the productivity distribution produce for the foreign market using high-technology. Since this technology is skilled-biased, exporters that resort to modern technologies are more skill intensive. Empirical evidence is also provided to support the model's main predictions using plant-level panel data from Chile's manufacturing sector (1990-1999).