Implementing class choir in primary schools to promote mental health: a mixed methods feasibility study of the everyone can sing intervention using the CFIR framework

Schools are increasingly recognized as key arenas for supporting children’s mental health. While many studies have examined preventative interventions, we know relatively little about how singing‑based programs are implemented in school settings. Everyone Can Sing (ECS) is a school-based class choir intervention developed through a four-year prototyping process in a Danish primary school to enhance mental health through inclusive, co-facilitated singing sessions. This mixed methods feasibility study examined barriers, facilitators, and contextual determinants influencing the implementation of ECS in the prototyping school, alongside two Danish public primary schools. We conducted an exploratory sequential mixed methods study in three Danish primary schools, including the original prototype school and two schools newly implementing ECS, involving a total of 902 children (aged 5–10) across 40 classes, along with their 40 teachers and 7 choir leaders. Guided by the Consolidated Framework for Implementation Research (CFIR), we explored how contextual determinants shaped implementation processes and outcomes. The qualitative phase included participant observations of class choir sessions and 26 interviews ( n = 51 participants) with school managers, teachers, choir leaders, and school children. These findings informed a CFIR-inspired survey administered to teachers, parents, and children to assess implementation outcomes: acceptability, feasibility, appropriateness, and sustainability potential. Data were analyzed thematically (qualitative) and descriptively (quantitative) and integrated through a weaving approach. Five integrated meta-inferences emerged. First, acceptability diverged across stakeholder groups: adults expressed strong satisfaction, while children’s views were more mixed, revealing enjoyment alongside fatigue and boredom. These dynamics highlight emotional resonance (joy, tiredness, ambivalence) as a determinant not captured in existing frameworks. Second, rigidity in intervention design challenged feasibility. Third, missing collaboration infrastructure generated “hidden labor” borne by teachers and choir leaders. Fourth, leadership commitment and teacher buy-in were key facilitators, and fifth, uncertainty about direct mental health effect weakened long-term commitment. The implementation of ECS was shaped not only by structural and relational determinants but also by children’s affective engagement. Including children’s perspectives revealed important differences in how the intervention was experienced compared with adult stakeholders, suggesting that affective dynamics, conceptualized here as emotional resonance, may deserve greater consideration within implementation frameworks such as CFIR. More broadly, this study contributes to implementation science by highlighting how contextual fit, collaboration infrastructure, and emotional resonance interact in the real-world delivery of universal, music-based school interventions. ClinicalTrials.gov, ID: NCT06204029, registered January 2nd 2024.