The purpose of the research project is to analyse and compare the contents, methods and working practices of social impact assessment (SIA) in regional land use planning in Finland. In Finland, there has recently been new developments in this area, whereas other Nordic countries do not have so much empirical cases. The research task is divided into the following subquestions: a) What are the contents and methods of social impact assessment in regional land use planning? b) How is social impact assessment integrated into the regional planning process and decision-making? c) How can plan-making benefit from social impact assessment? Does social impact assessment alter the planning processes and the contents of regional plan-making? If so, what does this mean? In other Nordic countries the role of regional land use planning is somewhat different from the Finnish model.