This study used a sample of 336 households and community-level data from 30 communities around Gonarezhou National Park in Zimbabwe to analyse the association between institutions and cooperation (defined as the ability to self-organise) and the relationship between cooperation and success of biodiversity outcomes. Using both ordinary least squares and instrumental variables estimation with heteroskedasticity-based instruments, our results confirmed that sound institutions are indeed an important ingredient for cooperation in the respective communities and that cooperation positively and significantly affects biodiversity outcomes. Community-level trust, the number of stakeholders, punishment and group size were found to be important variables explaining cooperation. From a policy perspective, our results show that external enforcement of rules and regulations does not necessarily translate into sound ecological outcomes; rather, better outcomes are attainable when punishment is endogenized by local communities. This seems to suggest that communities should be supported in a way that promotes the emergence of robust institutions that are tailor-made to suit their local needs; this will, in turn, facilitate good environmental husbandry. Cooperation, training, benefits, distance from the nearest urban centre, distance from the fence of protected areas, social capital, average age of household head, new electric fencing and information sharing were found to be very important variables explaining the success of biodiversity outcomes. Government programmes should target capacity building in terms of institutional capacity and skills development in order to have a positive impact on biodiversity. Both stakeholders (e.g., non-governmental organisations and government) should have a role in capacity building; these roles should complement each other to ensure that the necessary resources are mobilized and all communities receive the necessary training.