Marine Protected Areas (MPAs) are a common approach to conservation and marine spatial management, but they may not always be placed in the most beneficial locations. Current MPA guidelines lack consideration of socioeconomic factors, which makes it difficult to determine where MPAs would be most effective. This thesis aims to identify socioeconomic factors that influence MPA effectiveness, develop national-level indices to determine where large-scale MPAs are most effective, understand how village heterogeneity affects fishers' ability to adapt to MPAs, and identify individuals who are most vulnerable to being negatively impacted by MPAs. The study identified 32 factors that influence MPA impact, developed two national-level indices to represent potential opportunities and challenges for large-scale MPAs, and created a Livelihood Impact Potential Index (LIPI) to describe the degree to which a fisher might be vulnerable to MPA-related restrictions on their livelihoods. Results from this research can support MPA practitioners in developing MPAs that maximize ecosystem and livelihood benefits. The study used a systematic review of ten years of scientific literature and a case-study approach to collect data on the socioeconomic factors that influence the effectiveness of MPAs. The research also explored the appropriateness of MPAs as tools for supporting marine ecosystems and associated livelihoods in different socioeconomic contexts. This study contributes to the existing MPA literature by highlighting the importance of considering socioeconomic factors in conservation planning and MPA placement.