The reviews identify three issues of key importance to the development and success of MPAs for conservation and management. First, MPAs hold strong promise for management and conservation objectives, but the historical pattern of haphazard design, implementation, enforcement and evaluation has often produced equivocal and sometimes contradicting evidence for both their ecological effects and their effectiveness at achieving their intended objectives. Second, our understanding of many of the critical population and community processes that bear greatly on the consequences of this approach (e.g. dispersal, recruitment, direct and indirect effects of competition and predation) suffers from a lack of strong empirical studies and a comprehensive theoretical framework. Third, the global growth of interest in MPAs and concern for rapid development of organized systems of MPAs is great. Taken together, these three issues identify an urgent need for a well-developed theoretical framework, more rigorous empirical studies motivated and directed by theory, and actual implementation of systems of MPAs that will allow for proper evaluation and an evolution toward optimal design.There remain many challenges to managers, conservation scientists (biologists, ecologists and social scientists), and economists for designing, implementing and evaluating networks of MPAs.Because of the open nature of most populations and communities of coastal marine species, dispersal of reproductive propagules is critical to the objectives, design and evaluation of any MPAAnother fundamental objective for ecologists will be to predict the consequences of MPA protection, relative to continued exploitation, on the structure, dynamics and function of populations, communities and ecosystems.The complexity of ecosystems targeted for protection by MPAs create real challenges for evaluating their effectiveness for achieving desired conservation or fisheries goals.