The purpose of this formative performance evaluation of the United States Agency for International Development’s (USAID) ocean plastics portfolio was to assess program implementation to date and provide valuable insights to inform the SOS Initiative, which aims to address the escalating levels of plastic pollution worldwide. Outcomes of the performance evaluation include recommendations such as continuing to empower local actors, combining palliative interventions such as beach cleanups and river traps with data collection to help upstream policy, funding local solutions that have a material impact on plastic reduction, strengthening policy linkages, continuing to invest in technical assistance and knowledge exchange, continuing to adapt and apply tools and training, customizing program design for small islands and underserved areas, focusing on reductions, refillables, and alternatives to tackle low-value plastics, advocating and providing technical assistance for extended producer responsibility (EPR) frameworks, and creating enabling environments for reduction policies through applied research and incentive structures.