We use experimental data collected in 8 African countries to investigate whether a decentralized approach can promote the adoption of agricultural innovations. This participatory model is based on the creation of so-called ‘innovation platforms’ where local stakeholders meet and seek to identify problems and prioritize solutions. While we document evidence that the participatory model robustly promotes the adoption of crop management innovations across all research sites, we do not find significant effects for other domains of innovation. We also document considerable heterogeneity in terms of local priorities, and show that not all innovation platforms are equally successful. We present tentative evidence that the performance of these platforms depends on specific dimensions of ex ante social capital.