This paper presents the results of an exploratory study into how different forms of social capital embedded within community-based social networks may affect innovation in smallholder farming systems to better support food security in the Caribbean. Focusing on two rural communities in the small island developing nation of Saint Lucia, our results indicate the strong presence of interpersonal agricultural knowledge networks operating to: 1) facilitate farmer-tofarmer knowledge exchange; 2) increase farmer access to information; and 3) connect farmers to sources of support. In both communities, 'peer farmers' were reported as being the primary source of new agricultural knowledge for farmers, with government 'extension officers' the secondary source. Comparative social network analysis reveals how different forms of social capital within the two agricultural knowledge networks can affect self-reported farmer innovation in different contexts. Based on these findings we identify a number of opportunities for policy initiatives to better support, coordinate and enhance innovation opportunities among smallholder farmers in the Caribbean with a view to building their adaptive capacity in the face of environmental change. The findings provide important evidence and insights relevant to the governance of domestic agricultural systems and regional food security programming in the Caribbean.