<p>African innovators typically suffer from severe resource constraints and need to develop strategies to cope with these constraints. This paper focusses on external knowledge sourcing and, in particular, on the role of cooperation as a means to compensate for missing resources. Findings suggest that domestic inter-firm cooperation is of outstanding importance for firm-level innovation in Nigeria, whereas cooperation with other partners (research institutions, foreign firms, consultants, or the government) has no sizable impact on the innovative performance of Nigerian firms. Moreover, we show that it is in particular young firms and firms suffering from financial constraints that benefit from cooperation, whereas foreign-owned firms benefit less. Our findings contribute to a better understanding of the drivers of firm-level innovation in sub-Saharan Africa and have important implications for firm strategies and innovation policy.</p>