Investment planning is a decision-making process with specific characteristics. It is often seen as a rational quest for solutions that are in the public interest, and the dominant discourse tends to be technical and economic. Public documents reproduce this picture of a decision-making process based on rationalist premises where analytical methods and objective facts form the basis for decisions. Behind this purely rationalist façade, however, planning is also a highly political process where various actors try to impose their will on others. This aspect of the planning process is characterised by a less rationalist and more pragmatic way of thinking. The overall aim of the dissertation is to explore the tension between rationalism and pragmatism in decision-making and to investigate the manifestations of these aspects in the instruments that govern planning processes. Special emphasis is placed on decision-making processes involving multiple tiers of government. The research presented in the dissertation has been carried out as a case study of the planning of road and railway investments in Sweden. One part of the empirical analysis focuses on the historical-institutional development of investment planning from its introduction in the 1950s to the present day, with a special focus on the planning instruments involved. A second part of the analysis focuses on the decision-making process that resulted in a major investment plan presented in March 2010, with special emphasis on local and regional co-financing as a new and highly pragmatic instrument used in the process. The dissertation shows that a shift towards more pragmatic views has taken place during the last couple of decades. New financial arrangements are an indication of such a dynamic change.