Thesis: This thesis is composed of three chapters that have in common the question of export quality in a developing country context. The thesis focuses on different aspects of improving the quality level of exports. The first chapter is devoted to the impact of Aid for Trade on the quality of exports from recipient countries. It suggests a positive effect of Aid for Trade policy on the quality of exports. The second chapter focuses on the quality assurance role played by intermediaries in international trade. The results indicate that only specialized intermediaries play this role. The third chapter examines the link between firms' export orientation and their innovation performance. The empirical analysis shows a reduction in R&D investment by exporters whose sales reorient towards exports to the detriment of the domestic market, especially as they face high demand uncertainty. These unfavourable developments could nevertheless be overcome if the company has a long trade experience or high productivity. The three main results of this thesis are that aid for trade and the rise of specialized intermediaries contribute to the rise in quality of exporters, while the uncertainty of external demand tends, on the other hand, to hinder innovation by exporting firms.