The aim of this study was to assess the quality of the processes of a Youth-led Participatory Action Research (YPAR) citizenship education project by examining a 2-year intervention that involved 43 Italian high school students. We collected qualitative data (focus groups with students and interviews with teachers) to capture participants' perspectives, as well as longitudinal quantitative data to monitor the process over time (assessing school climate, perceived quality of participation, and group participation norms). The results revealed that YPAR was successful in reducing hierarchy, facilitating group activities, and recognizing youth voice, thus changing students' perception of their school environment and views on participation and active citizenship. The intervention also changed teachers' perceptions of students. YPAR proved to be a suitable option for citizenship education in school.