This case explains how qualitative comparative analysis has been used for a study of more than 60 voluntary programs in urban climate governance in 13 cities in Australia, India, Malaysia, the Netherlands, Singapore, and the United States. The number of cases is too small for traditional quantitative research approaches (variable or condition oriented) but too large for traditional qualitative approaches (case oriented). Qualitative comparative analysis is a configurational method, bridging the strengths of variable-oriented and case-oriented approaches, and provides a logic and tools for medium-n comparative research. This case study specifically illustrates (1) the strengths of qualitative comparative analysis studying equifinality, conjuctural causality, and data asymmetry; and (2) how qualitative comparative analysis can be used, within one study, for theory testing as well as theory development. Although the case does not assume that readers have working experience with the method, it is not meant as a first introduction to the method.