Orchestral playing is a central practice within Western European classical music. Previous research in the field of orchestral musicians’ learning and knowledge has mainly focused on students’ learning orchestral playing. Working conditions and work-related problems were also emphasized in previous studies. This thesis, however, focuses on professional orchestral musicians’ knowledge and learning. The method to investigate these issues was to let musicians verbally describe their professional experiences and orchestral practice. Interviews with a low degree of structure were conducted with four orchestral harpists from renowned orchestras. In the analysis and interpretation a hermeneutical approach was used. This approach also offered guidelines for considering the researcher’s role and pre-understanding. The findings showed that skilled musicians developed their knowledge throughout their careers. Knowledge of orchestral playing was contextually based, and based on experience. All skills used by the musicians when playing in an orchestra had to be contextually adapted. A main finding was how musicians were able to create, by their knowledge, a space for musical freedom and personal interpretation when playing in the orchestra. There were also knowledge issues that always had to be maintained and others that constantly had to be developed within practice. In conclusion, there are major contradictions that are important elements of the profession of orchestral musicians. The musicians should have a personal musical expression as well as a highly developed ensemble skill. They should focus on the extreme detail and the totality of the performed musical piece at the same time. They have to be able to express themselves musically within a restricted framework. This framework, and the interspace between the frames, can be negotiated by knowledge, skills and the choices of the musician.