Purpose: Over the past decades numerous policies, programmes and interventions have been undertaken to increase students' participation in physical activity in school. Research shows that intervention effects are mostly related to the way in which the program or policy is implemented, nevertheless, few studies have focused on the implementation process. Thus, this paper aims to explore and identify key implementation successes and barriers as perceived by principals, project leaders, teachers and students. Design/methodology/approach: A case study of eight schools participating in the Norwegian project "Physical activity and healthy school meals" was conducted, applying a qualitative approach. Findings: Findings show that all schools managed to ensure extra time for physical activity, varying from 20 to 45 minutes per day. None managed, however, to fulfil the recommendation of 60?minutes daily. Factors promoting the implementation were related to formalisation and anchoring in terms of policy plans and establishment of a project group, while factors hindering the implementation were related to lack of competence and confidence among teachers and lack of allocated time from school leaders. Practical implications: National, regional and school level structural conditions, in terms of time allocation and competence building, seem to be important targets for interventions aiming at facilitating daily physical activities in schools. More specific, governmental allocation of targeted schedule time seems also to be important. Originality/value: The identification of factors influencing implementation efforts aiming at enhancing physical activity can help practitioners to address such barriers and thus contribute to better implementation of physical activities in schools.