The role of entrepreneurial networks in the development of Small and Medium-sized Enterprises (SMEs) and the associated entrepreneurial activities are a core topic in both the networks and IMP literature. However the effectiveness of these networks remains little understood. This paper investigates a specific form of formal entrepreneurial network: the supportive networks among companies. More precisely, it seeks to identify the key factors of success and failure of these networks in their actions to support small and new business development by focusing on the interactions between the three categories of actors embedded in these networks. Eleven case studies were undertaken focusing on three French supportive networks between companies. The results showed that convergent interests - altruistic as well as economic - shared both between and within companies is the overarching reason why supportive action succeeds. We also found that interactions driven by non-trading interests contribute favourably to the development of the dynamics of these networks
