The U.S. Climate Change Science Program is in the process of producing 21 draft assessments that investigate changes in the Earth's climate and related systems. These assessments are designed to inform decisionmakers about the scientific underpinnings of a range of environmental issues, such as stratospheric ozone. This National Research Council report reviews one of these assessments, Synthesis and Assessment Product (SAP) 2.4, Trends in Emissions of Ozone Depletion Substances, Ozone Layer Recovery, and Implications for Ultraviolet Radiation Exposure. This assessment is noted as being the first-ever attempt to look at the United States contribution to ozone-depleting substances and ozone recovery. This National Research Council book commends the assessment's authoring team for comprehensively covering the scientific basis of ozone and ozone-depleting substances, but recommends several ways that the assessment could be improved. Suggestions include clarifying the discussion on climate effects of ozone and revising the approach to estimating U.S. contributions to production, consumption, and emission of ozone-depleting substances. The assessment could also be improved by reorganizing and editing to accommodate intended audiences.