Using firm level data from five countries-Brazil, Ecuador, South Africa, Tanzania and Bangladesh-this paper examines the knowledge-based determinants of productivity of firms active in food processing, textiles, and garments and leather products. In particular, it seeks to investigate the importance of various sources of knowledge in explaining productivity in the different industries. The knowledge sources driving productivity performance are very different across sectors. In food processing, firm productivity is most strongly affected by quality of management and foreign ownership linkages. In textiles, firms raise productivity levels by importing new machinery and through research and development. In garments and leather products, R&D and design activities, high quality management and licensing technology from foreign firms are significant productivity determinants. Firms' productivity levels are further depressed by regulatory and financial constraints.