In recent years, the widespread availability of sensor-provided smartphones has enabled the possibility of harvesting large quantities of data in urban areas exploiting user devices, so enabling the so-called crowdsensing that allows to realize complex applications impossible without the involvement of the research community. While many efforts have been made to improve specific techniques - spanning from signal processing to the assignment of data collection campaigns to users, and to the entire data processing - to the best of our knowledge, there are no active experiments aimed to explore the challenging issues raised by the management of large-scale crowdsensing campaigns as real-world experiments. This paper presents the ParticipAct platform and its ParticipAct living lab, an ongoing experiment at the University of Bologna that involves 170 students for one year in several crowdsensing campaigns that can access passively smartphone sensors and also prompt for user active collaboration. In this paper, we describe the guidelines behind the design of ParticipAct, its features, its architecture, and report quantitative results that assess and confirm the feasibility, obtained via intelligent coordination and management of crowdsensing campaigns.