Workplaces across Europe experience increasing problems with work-related strain and stress. Consequently, they are confronted with the need for stress-preventive interventions that target the sources of stress. A matter of current debate is how to continuously evaluate an organizational-level intervention and gain insight into progress and participants' perceptions of its impact; however, empirical data are lacking. Therefore, we conducted a qualitative study in three workplaces-two in information technology (IT) and one in manufacturing-to explore the design, evaluation process, perceived impact, and employees' experiences with the continuous use of a physical evaluation tool (visualization object) during an organizational-level intervention process. We conducted observations, surveys, semi-structured interviews and chronicle workshops across all three workplaces.Overall, the results showed that the visualization object proved successful as a tool to explicate and combine participants' perceptions of impact. The evaluation process also clarified that participants initially had different understandings of the intervention's purpose. However, the study also showed that the visualization object facilitated a dialog among participants, converging the different understandings to create a shared understanding and compliance of purpose. Finally, the respondents reported that the evaluation tool acted as a collective reminder of the intervention and the related changes. We conclude the study by providing recommendations for future evaluations of participatory organizational-level interventions.