The Incredible Years® Teacher Classroom Management program (IY-TCM) is an evidence-based program with documented effectiveness and positive outcomes for teachers, children and parents. However, most of the research relies on quantitative approaches, with fewer qualitative studies exploring teachers’ personal perspectives. The aim of this study is to explore the teachers’ experiences when they got training on the IY-TCM. This study was a qualitative study and involved 11 preschool teachers who participated in two focus groups. The first focus group was conducted before the teachers started the IY-TCM training and aimed to assess the challenges they were facing in their classrooms and their expectations for the training. The second focus group took place two weeks after the teachers had completed the training and aimed to evaluate their perception of the training’s impact on children, parents, and themselves. Results indicated that, before the training, the teachers reported several behavioral challenges in their classrooms, felt exhausted and were concerned about the lack of parental involvement in the educational process. They were also enthusiastic about the training. After the training, they identified several changes: children had become more empathetic and self-regulated, and parents were more engaged in the educational process. Furthermore, teachers felt more self-confident/controlled, valued the management tools they had acquired during the training, and appreciated the sharing and support. Effective improvements were evidenced in children, parents, and teachers, underscoring the recognized effectiveness of the IY-TCM program.