Over the past 15 years, the Deepwater Horizon (DWH) Trustees have invested $3.28 billion in a diverse portfolio of large-scale restoration actions across the Gulf of America region. This portfolio includes extensive coastal habitat restoration efforts in all five Gulf states; nutrient reduction and other water quality improvements; collaborative efforts with Gulf fishermen to reduce unintentional mortality to non-target fish and other marine species; marine debris removal; and the expansion of sea turtle and marine mammal stranding networks and emergency response capacity, among other restoration approaches. To fully assess the impact these restoration actions are having on the marine resources and ecosystems damaged by the spill, NOAA is synthesizing relevant ecological information across multiple spatial and temporal scales. Synthesis efforts focus on two main questions: 1) How has habitat restoration helped restore injured fish and invertebrate species? and 2) How have restoration projects reduced the level of risk that major stressors and threats pose to marine resources injured by the DWH oil spill? To address these questions, monitoring data collected for individual restoration projects is being synthesized along with new regional and Gulf-wide monitoring data collection efforts initiated by the Trustees, data from other Gulf science programs, and previously existing regional monitoring datasets. NOAA’s synthesis efforts incorporate a range of analytical approaches, including meta-analysis, food web analysis, quantitative models, spatial analysis, and expert elicitation. This multi-faceted approach will build the multiple lines of evidence necessary to understand long-term restoration outcomes against the background noise of a busy and ever-changing Gulf, helping us demonstrate the impact of the restoration investments and informing future restoration and marine resource management.