This paper presents the results of research carried out during the first stage of the Polish education system transition process initiated by the education reform of 2017. The study was conducted with teachers of schools to be dissolved, who decided to transform their institutions into a new type of school -general education secondary school (lyceum), while retaining staff and organizational resources of the hitherto middle schools (gymnasium). A processual approach adopted in this project allowed me to capture the changes as they were happening and the analysis of the conditions of transition trajectories.