This paper presents results of research that has developed a set of diagnostic and decision-support tools for assessing sanitation services city-wide. It highlights features of the tools and illustrates key results from their validation through application in five cities worldwide. Collective use of these tools reveals and explains the complexities of the enabling environment and political economy within which sanitation services are delivered. Results present not only the status quo of services but also reasons for them being so. The tools have proven effective in guiding the collection, analysis and discussion of evidence, as a precursor to detailed feasibility studies, necessary to ultimately plan appropriate city-wide sanitation interventions.