The aim of this article is to analyse the transposition processes involved in a new educational program of a management curriculum (Science et Technologie de la Gestion) and more specifically its implementation by two teachers using the same textbook This new program introduces new knowledge from psychology and a new pedagogical method: Observation-Analysis-Concept (OAC). We analyse four steps of the so-called didactical transposition for two new introduced concepts: ” attitudes and behaviours”. First step is an analysis (a priori) of these concepts of psychology, which shows two kinds of obstacles for the construction of the knowledge. In a second step the official curriculum has been analyzed. In a third step, textbooks resources are screened and analyzed and in a last step different effective teaching practices of two teachers of economics and management are observed and analyzed. Didactical contract analysis allowed us to examine the respective role of teachers and high school students when the latter build knowledge according to the OAC approach. We explore the way the teachers, the curriculum designers, and the authors of textbooks are confronted to epistemological obstacles involved in these specific psychological concepts. We also discuss how the teachers and the authors of textbook face the injunction of implementing the OAC approach vector of additional difficulties.