This paper examines preschool teachers’ experiences of participating in a preschool mathematics implementation study, as well as how the role of facilitators was perceived during the implementation process. The study draws on data from 21 focus group interviews and a digital survey. The results show that many preschool teachers interpreted the implementation through the lens of professional development, emphasizing collaboration, reflection, leadership engagement, and institutional support. This interpretation created tensions between teachers’ expectations of guidance and feedback and the implementation design’s intended emphasis on teacher autonomy. The findings further demonstrate that implementation quality is not only a matter of what is implemented, but also about how it is taken up, by whom, and under what conditions. A well-functioning local organization, including leadership support and opportunities for collaboration, emerged as a critical factor for meaningful and sustainable implementation.