Chapters 3, 4, and 5 discuss lessons learned from an extensive review of the existing literature dealing with the effectiveness of dispersants, as well as the fate and effects of dispersed oil, with a major focus on studies completed since the release of the 1989 NRC report Using Oil Spill Dispersants on the Sea. Chapter 3 provides a detailed discussion of relevant petroleum properties and geochemical processes and the mode of action of various dispersants. In addition, it includes an in-depth discussion of the current understanding of dispersant effectiveness and provides specific recommendations for developing an adequate understanding of effectiveness to support more informed decisions regarding dispersant use in nearshore settings. Chapter 4 explores physio-chemical and biological processes that control the dispersion and fate of oil droplets and thus constrain the concentrations of various petroleum compounds in the water column. In addition, the role of modeling and monitoring to better support decisionmaking is explored, and specific recommendations to improve information needed to support decisionmaking are provided. Chapter 5 provides an in-depth analysis of toxicological studies that focus on dispersants or dispersed oil. By summarizing the salient points from existing reports and recommending specific additional, needed toxicological work, Chapter 5 provides guidance on efforts to better understand the effects of dispersed oil—a key component of effective decisions involving difficult trade-offs among sensitive species or habitats. Chapter 6 summarizes the key findings and recommendations of the previous chapters and organizes them into what is intended to be a coherent research plan to inform and coordinate to the degree possible research carried out or sponsored by federal and state entities, industry, and academia.