BackgroundImprovement work can be used in preschools to enrich outdoor environment for children’s better health. Effective improvement work can facilitate the necessary changes, but little is known about professionals’ experiences of participation in improvement interventions. The aim was to evaluate how preschool staff experience quality improvement work, using the Breakthrough Series Collaborative improvement programme, to enhance outdoor environments.MethodsAn improvement intervention using a breakthrough collaborative was performed at 9 preschools in Sweden and examined with a longitudinal mixed method design. Staff completed questionnaires on 4 occasions (n=45 participants) and interviews took place after the intervention (n=16 participants).ResultsThe intervention was successful in the sense that the staff were content with the learning seminars, and they had triggered physical changes in the outdoor environment. They integrated the quality improvement work with their ordinary work and increasingly involved the children. The staff tested improvement tools but did not find them entirely appropriate for their work, because they preferred existing methods for reflection.ConclusionsThe challenges in quality improvement work seem to be similar across contexts. Using the Breakthrough Series Collaborative in a public health intervention is promising but needs to be integrated with preunderstandings, current reflections and quality tools and models.