Existing research on sport organizations is imprecise in the use of the concept of 'professionalization'. Furthermore, we do not know if analytical concepts of professionalization correspond with the understanding in practice. This study explores the perceptions of practitioners and proposes a framework to analyse professionalization in national sport federations. Expert interviews were conducted with six key people from Swiss national sport federations and then analysed these for characteristics of professionalization using a hermeneutic approach. The characteristics were divided into three areas: (1) changed management philosophy, (2) functional differentiation and specialization, and (3) application of management tools. However, professionalization is primarily perceived to be a matter of 'professional' attitude that transforms into federation culture. The practitioners disclose an ambivalent view of professionalization, e.g. business-like culture vs. voluntarism, for-profit vs. non-profit orientation, autonomy vs. control. A framework is developed that synthesizes analytical concepts and practitioners' perceptions to support future comprehensive research into causes, forms and consequences of professionalization in national sport federations.