The principle of multi-functionality simultaneously considers a variety of social, economic and environmental goods and services related to land use. It is thus a key to sustainable development of land and rural areas. Land use policies seek to support the economic competitiveness and sustainable development of rural areas. For efficient impact assessment, policy makers require tools for assessment of anticipated policy impacts on a wide range of sustainability issues across European regions. The European Union funded Integrated Project SENSOR develops ex-ante Sustainability Impact Assessment Tools (SIAT) to support decision making on policies related to multifunctional land use in European regions. SENSOR directly responds to the European sustainability objectives as applied to land use and rural development. This book provides an overview on the analytical approach in SENSOR and documents preliminary results. This includes the identification of end user needs for SIAT and the development of a first SIAT prototype. Methodological frameworks for scenario development and land use modelling including indicator analysis and web-based data management were established. Surveys of European sensitive areas and a regional spatial reference framework for socio-economic and environmental assessment were drafted.