Objective: Interventions promoting a healthy psychosocial work environment are common, yet little is known about participation and effectiveness of such measures. The aim of this study was to describe differences between participants and nonparticipants in the Sound of Wellbeing (SOW) initiative, including a variety of demographic characteristics, perceived work environment, psychological factors and self-perceived health. The study also compared the participants' and non-participants' retrospective perception of change in the psychosocial work environment and their health during the project period. Methods: In this cultural organizational-level intervention, employees in two county hospitals participated as singers with different hospital departments forming their own choir. The majority of employees (1431 employees; 57.4%) completed a survey questionnaire after the intervention, of which 426 (29.8%) had participated. Results: We analysed the differences between participants and non-participants on several descriptive characteristics, personality, engagement, commitment, general health and demand-control-support, as well as their self-perceived change in some of these variables. Lower participation was found among men, employees above 62 and below 38 years of age, part-time employees, university-educated workers and health care workers. Furthermore, we found more engagement, organizational commitment and self-reported positive change with regard to psychosocial work environment and global health in participants compared to non-participants. Conclusions: The intervention showed promising results for incorporating cultural activities in the work environment, but further investigation of the effectiveness of organizational-level interventions using a pre-post design is needed.