There is a global trend in the depletion of transient reef fish spawning aggregations ("FSAs"), making them a primary target for management with marine protected areas (MPAs). Here, we review the observed and likely effectiveness of FSA MPAs, discuss how future studies could fill knowledge gaps, and provide recommendations for MPA design based on species' life history and behaviour, enforcement potential, and management goals. Modelling studies indicate that FSA MPAs can increase spawning-stock biomass and normalize sex ratio in protogynous fish populations, unless fishing mortality remains high outside protected FSA sites and spawning times. In the field, observations of no change or continued decline in spawning biomass are more common than population recovery. When empirical studies suggest that FSA MPAs may not benefit fish productivity or recovery, extenuating factors such as insufficient time since MPA creation, poor or lack of enforcement, inadequate design, and poorly defined management objectives are generally blamed rather than failure of the MPA concept. Results from both the empirical and modelling literature indicate that FSA MPAs may not improve exploitable biomass and fisheries yields; however, investigations are currently too limited to draw conclusions on this point. To implement effective FSA MPAs, additional modelling work, long-term monitoring programmes at FSA sites, and collections of fisheries-dependent data are required, with greater attention paid to the design and enforcement of area closures. We recommend a harmonized, adaptive approach that combines FSA MPA design with additional management measures to achieve explicitly stated objectives. Conservation objectives and, therefore, an overall reduction in mortality rates should be targeted first. Fisheries objectives build on conservation objectives, in that they require an overall reduction in mortality rates while maintaining sufficient access to exploitable biomass. Communication among researchers, regulatory agencies, park authorities, and fishers will be paramount for effective action, along with significant funds for implementation and enforcement.