The aim of this study was to analyse how a model for practitioner-oriented research can be used as a tool for professional development in the preschool. The focus of interest is the type of knowledge that is formed when researchers and preschool staff cooperate on local projects, and what this new knowledge means for the images of professional competence among staff and their regard to the research concept. The intention was to gain useful knowledge from experiences critically reflected in a team, related to theory and tested in local practice. The participants consisted of fifteen working-teams from preschools in two Swedish cities, together with three university-based researchers. After an introduction from the researchers, each team chose a theme. This was grounded in their local practice and was done over a period of eight months. During this period, the staff regularly met with each other in mixed groups and had supervision from the researchers. The results from the projects were documented and presented for all participants. The researchers further analysed these documents. Before and after the project, participants were asked to complete a questionnaire and were interviewed once. The results showed that the staff generally had a positive picture of the relevance of research-based knowledge for their developmental work, and increased their ability to use the group for constructive critical reflection on their professional work in preschool. The results are also discussed in relation to theories of group learning and situated learning.