This paper documents how the implementation of forest tenure policy affects the decision-making of farmers in mangrove-shrimp farming systems with regard to their access to and management of mangrove forest in Ca Mau, Mekong Delta, which is the largest remaining mangrove forest in Vietnam. Policies on land allocation, land tenure and use-rights are important since they potentially promote sustainable mangrove-shrimp management. Forest management policy in Vietnam has been changed to promote equality of benefit sharing among stakeholders and devolved State forest management to the household level. However, to what extent its implementation can stimulate both mangrove conservation and livelihood improvement is still being debated. We use access and its social mechanisms to investigate how State Forest Companies (FC) and farmers can benefit from mangrove exploitation. The study was conducted from September 2008 to August 2010 using both qualitative and quantitative methods and using a participatory approach. After group discussions and in-depth interviews with a wide range of stakeholders, we interviewed 86 households in four communities using structured questionnaires. Results show the imbalance in access to finance, markets, and differences in authority between the two actors, farmers and FC. The discussion focuses on the possibilities of “win–win” outcomes, i.e. land tenure regimes promoting the devolution of sustainable forest management to farm households to balance benefits of both mangrove conservation and livelihood improvement.