Workshops play a central role in the application of planning support systems (PSS) in collaborative planning practice. We conceive of workshops as socio-technical settings in which the characteristics of the PSS instrument are mediated by different factors, such as group dynamics, facilitation and tool involvement by the participants, to result in outcomes desirable for planning. We argue that it is critical to develop an understanding about the definition, facilitation and evaluation of PSS workshops. This chapter sheds light on these aspects of PSS workshops through a detailed discussion of existing empirical research on the topic, as well as our own empirical experience. This includes two brief vignettes of PSS workshops with the PSS Envision Tomorrow in the United States and Urban Strategy in the Netherlands. The chapter concludes with a critical reflection on the role of academic research in initiating and evaluating PSS workshops.