International trade learning and firms heterogeneous performance : theory and evidence from developing economies This thesis investigates whether Chinese firms improve their productivity through export and why this is the case; whether export and R&D investment have a complementary effect on improving firm performance; how to identify the dynamics of technological capabilities for a large group of firms and how different channels of foreign technology influence the transitions of firms in Central Asia and Eastern Europe. The evidence in chapter 2 does not support that export leads to higher productivity for manufacturing firms in China. However in order to penetrate the international market firms conduct more product innovations when foreign sales are initiated. The failure of exporters to increase their productivity can be explained by their prominent usage of labor and by a lack of R&D investment in absorbing advanced technology.