Full text can be accessed at http://www.inderscienceonline.com/doi/abs/10.1504/IJSSOC.2014.057888Although Marine Protected Areas (MPAs) provide an increasingly popular policy tool for protecting marine stocks and biodiversity, they pose high costs for small-scale fisherfolk who have few alternative livelihood options in poor countries. MPAs often address this burden on local households by providing some benefits to compensate locals and/or induce compliance with restrictions. We argue that MPAs in poor countries can only contribute to sustainability if management induces changes in resource-dependent households’ incentives to fish. With Tanzania’s Mnazi Bay Ruvuma Estuary Marine Park (MBREMP) and its internal villages as an example, we use an economic decision modeling framework as a lens to examine incentives, reaction to incentives, and implications for sustainable MPA management created by park managers’ use of enforcement (“sticks”) and livelihood projects (“carrots”). We emphasize practical implementation issues faced by MBREMP managers and implications for fostering marine ecosystem sustainability in a poor country setting.