The main goal of the present study was to investigate the barriers to implementing the Norwegian national guidelines for healthy school meals as perceived by principals, project leaders, teachers and students. This study employed a multiple-case design using an explorative approach. Data were collected at three secondary schools in Norway participating in the intervention project Physical activity and healthy school meals. Individual interviews were conducted with school principals and project leaders, and focus group interviews were conducted separately with teachers and students. Four categories of barriers were identified: (1) lack of adaptation of the guidelines to the target group; (2) lack of resources and funding; (3) conflicting values and goals; and (4) access to unhealthy food outside school. The research identified differences in perceived barriers between the staff responsible for implementation and the students as the target group of the measures. All staff groups perceived barriers relating to both resources, and conflicting values and goals. The teachers were more concerned about issues of relevance for adaptation to the target groups than were the principals and project leaders. The students were concerned mostly with issues directly affecting their experience with items offered in the canteen.