This paper has two broad objectives: (i) To develop a model of GSS-enabled strategic planning based on Habermas? theory of communicative action, (ii) To apply the model as a problem-structuring device to the conceptual problem of designing the strategic evaluation of a comprehensive urban plan. The model, known as the VC or validity-claims model, provides separate evaluative criteria for personal, social and technical aspects. The criteria for successful GSS-enabled strategic planning may be summarized as: "personal commitment validated by personal truthfulness or sincerity to a social consensus validated by rightness for informed action validated by objective truth". Detailed criteria (viz., goal, strategy, procedure, issues, problems) are developed for each type of validity claim and matched to the technologies available. The result is a detailed brief for the design of GSS-enabled strategic urban planning interventions, including a sample agenda for the GSS-supported meeting and the GSS tools that will be employed.