During the last ten years education for social work underwent deep changes due to the new references generated by the Bologna process. In Switzerland, these transformations are answers to a policy of valuation of the professionaleducation and of the adaptation of contents to the needs of economic circles and to the need to increase international mobility. Thus, the creation of the High Specialised Schools (HSS) convey the ambition to answer the needs of profesional practices through high level missions in the domains of education, research and service performance. Since the implementation of the bachelor system in the HSS, the multiplication of education levels results in a newhierarchical organization of the professions in the field of social intervention and entails the risk of a division of the professional acting. Our thesis project hence joins these major transformations by empahsyzing, primo, the contents of curricula to be given in a university of professions - the first mission of which is to answer the needs of the employment market - and, secundo, the joining of tacit skills and acquisition of know-how belonging to the professional practices, in a perspective of formalization of the incorporated knowledge, of its modalities and its limits, which, from our standpoint, constitutes the major concern of the profesional education at the university level. Concretely, our investigation is about the acting of social educators who are involved in situations allowing the apprehension of the complexity of these situations where institutional, profesional and personal elements are interfused in daily actions. Having paid attention to thedialectics between social control and development of the person, we have tried to understand the consequences of such positions in the accompanying of the youths placed in a shelter. The analysis of the empirical data is the core of the thesis. Starting from indirect methods, we explore three profesional situations in order to reach the hart of the activity and, thus, allow the readability of the action’s complexity. Taking into account situations wherein the educators are involved, then, enriching them by theoretical contributions, we have particularly seeked to maintain a coherence between the epistemology of the clinical approach to activity and the methodological building of our approach, in order to grasp the key dimensions of the acting. [...]