Participation on social life has not only a high significance in Clinical Social Work, but also comes to the fore in society. For that reason, this master thesis will deal with the International Classification of Functioning, Disability and Health of the World Health Organization, which is based upon the biopsychosocial model. The work will respond to the question, with which emphasis the ICF can be involved in social diagnosis and how it can contribute to goal orientation in clinical-psychosocial casework. In addition, the question how the ICF developed will be answered. In the theoretical part of this work, the emphasis will lay on social diagnosis in Clinical Social Work, the Family of International Classifications and its reference classifications as well as the ICF. For the empirical field research, there were held six expert interviews with social workers and similar professions in the field of social work in Austria and Germany. The experts have been questioned about their field and the application of the ICF. The data set was evaluated and interpreted based on the grounded theory methodology of Kathy Charmaz. Hereby it became apparent, that the ICF is especially helpful to structure and display complex cases. Through the resource orientation of the classification and the personal and environmental factors, the needs and requests of the clients come to the fore. Concerning the question of the development of the ICF, the current German “Bundesteilhabegesetz” went into focus, as well as accompanying changes and challenges in many german organizations and the possible effects on Austria.