A marine protected area (MPA) potentially generates a wide range of consumptive use, non-consumptive use and non-use values that include: critical habitat protection, conservation of marine biodiversity, recovery of threatened and endangered marine species, increased recreational benefits and increased biomass of harvested marine species. To help assess whether such values exceed the potential costs of MPAs, this paper provides a policy-enabling framework that reviews the existing theoretical and practical instruments and approaches that can be used in the ex-ante evaluation of MPAs. This framework is in three parts. First, a range of alternative monetary and non-monetary techniques to estimate three key economic benefits of MPAs: consumptive, non-consumptive use and non-use values are presented. Second, three decision protocols that can be applied to determine the desirability of establishing MPAs are described. Third, caveats of these approaches and the necessity to accommodate social needs of the communities are provided. The framework shows that biological and ecological considerations together with economic viability and socio-economic factors can and should be taken into account when deciding about when and where to establish MPAs and of what size.