From September 2024 onwards we will start the development of an educational innovation for Dutch primary schools to design a dynamic school day (a school day in which sedentary learning is regularly interrupted by moments of physical activity) for their local context. A number of Dutch primary schools already successfully implemented a more dynamic school day. In this qualitative study, we set out to assess the facilitators and barriers that several stakeholders faced during the implementation of the dynamic school day. We also set out to assess preferences of pupils with respect to a more dynamic school day. In preparation of the development phase, we will conduct semi-structured interviews with stakeholders of 3 Dutch primary schools (spring 2024). The interview guide will be based on the MRC guideline for conducting process evaluations of complex interventions. For each school, we seek to include: 1) the physical education teacher, 2) a classroom teacher who finds it easy to organize physical activities during the school day, 3) a classroom teacher who finds it difficult to organize physical activities during the school day, 4) a member of the management team. If relevant, we will also interview other stakeholders involved in the implementation of the dynamic school day. We will present the factors that may facilitate or hinder the implementation of a dynamic school day in the Dutch context. We will use these results to develop a set of potential implementation strategies that can serve as a source of inspiration for other Dutch primary schools in their process to develop a dynamic school day for their local context.