Abstract This article presents an empirical study on a new training program for the professional development of school inspectors and principals. The international literature reviews show that training based on the learning of managerial skills has limits. Another approach to training based on professional difficulties experienced and on authentic practice is necessary for school inspectors and principals. The study explores the effects of the training program “NeopassCadres” on the professional development of inspectors and school principals. A qualitative research design elaborated from a practice perspective and based on self‐confrontation interviews with inspectors and school principals who participated in the program “NeopassCadres”. The results show the impact of the activity analysis on the professional development of inspectors and principals. The activity analysis is an opportunity to describe professional actions and difficulties, share experiences between peers, engage in professional debates on generic problems, identify progress in the practice, and assess the effectiveness of new actions. The study focuses on a case study in France. The number of participants is low; the results must therefore be supplemented by new studies on the impact of activity analysis on the professional development of inspectors and principals. The study contributes to the evolution of training for novice inspectors and novice school principals. The main contribution concerns the understanding of the process of professional development, linking it with individual and collective activity analysis. The other contribution relates to the evolution of the trainers' posture during viewing and analysis of videos. The study provides knowledge about training based on analyzing the “non‐visible” dimensions of actors' activity at work. The activity analysis method helps inspectors and school principals evoke difficulties, motives, intentions, and emotions.