Between 1999 and 2003, the Swiss Post carried out a decision support process concerning the reorganization of the network of post offices in 17 major Swiss cities. The applied decision support approach combined sociological survey tools, spatial analysis, and multicriteria analysis. It required very substantial resources in terms of data, skills, and funding. The first part of this chapter describes this decision support approach. The second part proposes a reflexive perspective. By adopting a constructivist approach to decision support, the focus is put on the interactions between the information produced and the actors involved in the decision process. We thus observe that this information has indeed significantly contributed to the modification of the postal networks of the cities treated, in particular as arguments during the negotiations that were carried out with the local actors of each city. We also observe that this information fed, inside the Swiss Post company, a learning process that led to a change of discourse and paradigm in the strategy for locating post offices in the cities. The decision support process, therefore, played a very important role in enabling the actors to better understand the territorial complexity that lies behind the reorganization of urban post office networks.