This chapter introduces the two cases.IPCity is about the design of a collaborative mixed reality application, aimed at supporting mixed teams of urban planners, politicians and citizens in using participatory technologies to create and manipulate design alternatives for real urban planning projects. Sisomis about an information system that allows patients – severly ill children – to report their symptoms on a mobile device, before consulting a doctor. The chapter provides a brief introduction to the two cases, focusing on their chronology and on details of the participatory process.