This chapter focuses on the role of surveillance in the policy process. It promotes a general framework to assess the effectiveness of health surveillance systems from a social science perspective, based on the concept of real governance. Effectiveness of animal health surveillance systems is addressed through the analysis of the gaps between, on the one side, the principles and the “official” rules and norms and, on the other side, their implementation in real life. Practically we suggest to assess the effectiveness of a surveillance system following two stages. First, we expose potential reasons that may explain a lack of compliance, from the informants of a surveillance system, with the "official rules" supposed to drive this system. Second, we identify and assess the “practical rules” that concretely drive the exchange of epidemiological information among local stakeholders (public or private) and the decision-making process (defined as the “practical surveillance system”). These practical rules or norms characterize the “real governance” (that is how, concretely, stakeholders are organized collectively and more or less informally), often associated with informality. Understanding the real governance gives the opportunity to identify alternative solutions built by stakeholders to address the different issues they are facing, and to assess the ability of these stakeholders to organize a collective action, sometimes in order to tackle the failure of the administration. Evaluation methods described throughout this book contribute to assess the relevance and the quality of the data, information and knowledge produced by the surveillance system. Surveillance besides its technical aspects raises social and political issues and questions. The general framework described in this chapter can bring to the development of innovative pragmatic surveillance tools and methods, as described in this book.