This research explores the mechanisms of the professionalization of primary school teachers in the Republic of Congo. Starting from a structural divide between trained teachers (ENI) and self-taught/volunteers, the study aims to identify how teachers reconcile the constraints of prescribed work (Official Instructions, preparation sheet) and the realities of actual work (overcrowded classes, limited resources). The methodological approach is qualitative, based on semi-directive interviews. The results reveal a professionalization of supply, characterized by strong individual resilience and dependence on horizontal mutual aid (GAP). The study shows that practice improvement is mainly hampered by the difficulty of mastering advanced didactic engineering, and by the ethical and logistical constraints associated with discipline management. Vertical coaching is the main catalyst for technical standards, but its effectiveness is limited by the irregularity of its visits. In conclusion, professionalization is a collective and dynamic act that needs to be supported by systemic reforms.