In order to tackle today's grand challenges, we need to better understand how social entrepreneurs (SEs) search for knowledge to solve complex social problems. However, existing search models in social entrepreneurship lack an explicit focus on complexity. To address this gap, our explorative study adopts concepts from organizational search within open innovation as our theoretical lens to analyse 18 narrative interviews with SEs in Germany and Ethiopia. Our findings provide empirical accounts for a social entrepreneurial search model integrating different search mechanisms and search heuristics. We identify three distinct types of SEs who apply the different search types focused search, tentative search and hybrid search based on their different complexity perceptions in different search environments and two distinct normative theories that guide their search as cognitive heuristics. We contribute to both research on organizational search and social entrepreneurship and our findings have practical implications for politicians, social entrepreneurs and educators.