This chapter assesses the impact of Swiss agricultural policy reforms on the economic and environmental performance of agriculture. OECD Policy Evaluation Model (PEM) is used to explore the impacts of policy reforms on production, trade and farm income. This Chapter also attempts to assess the environmental impacts of policy reforms, such as impacts on nutrient balances and surpluses, greenhouse gas emissions and biodiversity, making use of OECD environmental indicators and other data sources. Given the importance of sustainability and landscape objectives of the agricultural policies, the study also explores the use of PEM to assess the environmental impacts of agricultural and agri-environmental policies by incorporating spatial heterogeneity.