RESUMEN
In this article we reflect on the quality of a realist synthesis paradigm applied to the evaluation of Phase V of the WHO European Healthy Cities Network. The programmatic application of this approach has led to very high response rates and a wealth of important data. All articles in this Supplement report that cities in the network move from small-scale, time-limited projects predominantly focused on health lifestyles to the significant inclusion of policies and programmes on systems and values for good health governance. The evaluation team felt that, due to time and resource limitations, it was unable to fully exploit the potential of realist synthesis. In particular, the synthetic integration of different strategic foci of Phase V designation areas did not come to full fruition. We recommend better and more sustained integration of realist synthesis in the practice of Healthy Cities in future Phases.