Increased possibilities for physical activity among students during the school day is advocated for by many. Especially secondary schools seem to struggle with this task, with adolescence being a period of declining levels of physical activity and increased demands at school. School-based physical activity policies and programs often relies on school staff and teachers to deliver these innovations/initiatives. Earlier research shows that teachers’ and other staffs’ confidence to deliver physical activities for students are important for the adoption and implementation of physical activity programs outside of ordinary physical education class. However, to our knowledge, there are no earlier attempts to investigate how this relates to intraorganizational networks among school staff. Consequently, this study aims to explore school staff and teachers’ networks, knowledge, self-perceived competence and confidence in one's own capability regarding implementing daily physical activity for students in a Swedish secondary school. This case study applied a convergent mixed method design with an emergent approach, where the qualitative ethnographic data and quantitative survey data were collected around the same time. Data was collected during one full school year from teachers and other school staff at one secondary school (students aged 12-16 years, grades 7-9) in a larger urban area in Sweden. The sample included all staff within the school that interacts with secondary students, which involves school management, teachers and others who are responsible for secondary students at some point during the school day, involved in student health or are engaged in physical activity, as well as physical education and health teachers. Our empirical material consists of field notes (180 hours of fieldwork), transcriptions from interviews (12 staff), as well as survey questions and nomination data (23 participants). Analysis is ongoing; where qualitative data is being analyzed through a reflexive thematic analysis, and survey data through a social network analysis, combined in an integrated analysis. Our study contributes with insights on how school staff and teacher-level knowledge and capabilities may contribute to implementation success within school-based physical activity initiatives and policies. Given the unique mixed-method network design of our study, the study also provides important knowledge on how network characteristics and relations contribute further as facilitating or hindering factors for implementation of physical activities in school contexts. Considering the long-term sustainability and quality of school-based physical activity initiatives; teachers and staff networks and their capabilities are important aspects to contemplate.