This paper empirically highlights the important role of structural social capital in enhancing the propensity to innovate of firms. Specifically, it investigates, through a probit analysis, the causal effect of the set of relations owned by producers on their propensity to innovate. A case study is presented from the South of Italy. It concerns a sample of 32 organic farming operating in the area of Foggia, an administrative district in Apulia region. The findings demonstrate that the relations with organic associations and other local institutions significantly impact on the innovative performances of firms. The first section presents the state of the art on the innovation determinants in the agro-food system. The second section focuses on the role of social capital in innovation performance. It contains the description of the specific form of social capital investigated. The third part contains the specification of the model. The discussion of findings follows. Concluding remarks are reported in the last section.