Contemporary policy making calls for scientific support to anticipate the possible consequences of optional policy decisions on sustainable development. This paper presents an analytical framework for ex ante assessment of economic, social and environmental impacts of policy driven land use changes that can be used as an aid to policy making. The tasks were (i) to link policy scenarios with land use change simulations, (ii) to link land use change simulations with environmental, social and economic impacts through indicators, and (iii) to valuate the impacts in the context of sustainable development. The outcome was a basis for dialogue at the science-policy interface in the process of developing new policies on European level that impact on land and land use. The analytical approach provides a logical thread for ex ante impact assessment within the context of sustainable development, land use multifunctionality and land use change and it provides a thorough discussion of achievements and open challenges related to the framework. It concludes with considerations on the potentials for using evidence based ex ante assessments in the process of policy development. The paper is complemented by a B-paper providing exemplary results from two applications of the framework: a financial reform scenario of the Common Agricultural Policy of the European Union, and a bio-energy policy scenario for the case of Poland (Helming et al. this feature).