BACKGROUND: State primary schools present an opportunity to support children's physical activity equitably, however, many school-based physical activity interventions have been unsuccessful. Many interventions have focused on school built environments to increase or measure the physical infrastructure a school has. Yet literature suggests that broader social and institutional factors, such as school policies and staffing, are equally crucial for supporting pupil's physical activity. The aim of this study is to qualitatively explore and assess primary school staff perspectives on the role of school facilities and resources in supporting pupil physical activity and the factors that impact their use. METHODS: We conducted 33 semi-structured interviews with state primary school staff in the Bristol area, Southwest England, between November 2023 and January 2024. Staff roles included headteacher/principal (n = 5), deputy headteacher/principal (n = 6), class teacher (n = 7), teaching assistant (n = 2), Physical Education (PE) subject lead (n = 8), dedicated PE teachers (n = 4), and Parent Teacher Association chair (n = 1). Staff were recruited from 19 purposively-sampled schools with a range of school sizes, locations, and sociodemographic characteristics. Reflexive thematic analysis was used. RESULTS: Five themes were generated related to how school facilities and resources impact pupil physical activity: 1) Facilities and resources create potential for pupil physical activity, 2) A social context supportive of physical activity is needed to maximise this potential, 3) Logistical challenges undermine the potential of facilities and resources, 4) The potential of facilities and resources change throughout the school year, and 5) Facilities and resources are not always fit for purpose. CONCLUSION: The presence of facilities or resources alone does not determine pupil physical activity at primary school. Factors such as the social context of the school, logistical and timetabling challenges, seasonality, and how fit for purpose facilities are for that school, are important factors in school staff and pupils' use and management of these facilities, and whether their potential is maximised or undermined. Future research and policy must broaden the focus from the presence of facilities and resources for physical activity, to include a focus on how these are maintained and engaged with in a school's specific context.