Agri-environmental Indicators (AEIs) can contribute to the needs of policy makers and other users in a number of ways examined in this chapter. A brief overview is provided in Section 4.1 of recent developments in domestic agricultural support; agri-environmental policy measures; and multilateral environmental agreements affecting agriculture, in particular, drawing a link to the material included in the country sections of Chapter 3. Section 4.2 discusses how selected OECD countries and international organisations, including OECD, are using AEIs as part of their toolkit to report on the environmental performance of agriculture. A selective literature review in Section 4.3 examines how AEIs are being used by OECD member governments, the OECD and other international governmental organisations, and other researchers, in analysing the linkages between the effects of agricultural and environmental policies on environment outcomes. Finally, Section 4.4 highlights where key gaps exist in terms of knowledge, methodologies, and data which are limiting the use of AEIs for reporting the state and trends of environmental conditions in agriculture and as a tool in policy analysis.