This paper is a guide for citizens, scientists, resource managers, and policy makers, who are interested in understanding the economic and social value of marine protected areas (MPAs). We discuss the potential benefits and costs associated with MPAs as a means of illustrating the economic and social tradeoffs inherent in implementation decisions. In general, the effectiveness of a protected area depends on a complex set of interactions between biological, economic, and institutional factors. While MPAs might provide protection for critical habitats and cultural heritage sites and, in some cases, conserve biodiversity, as a tool to enhance fishery management their impact is less certain. The uncertainty stems from the fact that MPAs only treat the symptoms and not the fundamental causes of overfishing and waste in fisheries.