Social capital is one of the main determinants of the institutional capacity of local governments which can positively influence the impact of development policies and, ultimately, regional socio-economic performances. In particular, the economic backwardness and many unresolved issues in Southern Italy are often explained by low levels of social engagement. Open government data on projects funded by public money can enable new forms of engagement, like the citizen based monitoring of public policy. Citizen monitoring of development policies in Southern Italy can strengthen existing civic communities and create new ones. Furthermore, citizen monitoring has the potential to directly influence the quality of policy-making by collecting evidence on how projects are progressing. This evidence can be harnessed by local governments to improve the implementation of current policy and/or to plan new actions. The paper will analyze the case of "Monithon", an independent initiative aimed at monitoring EU and national policies for economic cohesion in Italy. Through this initiative, citizens are able to collect evidence on the progress and results of the projects funded by European and national Cohesion Policy in Italy, based on the official data from OpenCoesione, a governmental open data portal developed by the Department for Cohesion and Economic Development (Ministry of Economic Development).