This book has been developed as a textbook of decision support methods for s- dents and can also serve as a handbook for practical foresters. It is based on the research we have carried out and lectures we have given over the past years. We have set out to present all the methods in enough details and examples that they can be adopted from this book. For researchers who need more details, references are given to more advanced scienti c papers and books. In this book, theories of decision making and the methods used for forestry - cision support are presented. The book covers basics of classical utility theory and its fuzzy counterparts, exact and heuristic optimization method and modern mul- criteria decision support tools such as AHP or ELECTRE. Possibilities of analyzing and dealing with uncertainty are also brie y presented. The use of each method is illustrated with examples. In addition to decision aid methods, we present the basic theory of participatory planning. Both hard and soft methods suitable for partici- tory or group decision analysis are presented, such as problem structuring method and voting. The criticism towards decision theory is also covered.Finally, some real-life examples of the methods are presented. Annika Kangas Department of Forest Resource Management University of Helsinki Jyrki Kangas Metsahallitus .. Mikko Kurttila University of Joensuu v Acknowledgements Manyresearchersandstudentshavehelpedusbyreviewingchapters,suggesting- provements and even checking our example calculations. We would like to ackno- edgethesereviewers,Ms.AnuHankala,M.Sc.TeppoHujala,M.Sc.AnnuKaila,Dr.