Using the economic approach of social choice theory, this unique book examines difficulties found in democratic processes involved in the creation and implementation of planning policies. Social choice theory focuses on the hard trade-offs to be made between rationality in decision-making on the one hand, and political values such as democracy, liberalism and freedom from manipulation on the other. As an institution can be seen as a set of rules, the focus on rules and procedures of collective choice makes social choice theory well suited for analysing important political aspects of planning institutions. Special attention is given to communicative planning and the logical reasons why all the desirable properties of dialogue cannot be simultaneously attained. The analysis provides original and significant new insights into the process and the institutions involved. It highlights weak spots of present planning techniques and procedures and suggests further steps towards institutionally enriched planning theory.