This article presents the study of the perception of teachers and principals participating in a teacher training program about cooperative learning with the focus on the transformation of teaching practices for inclusive education. The aim is to analyze the effect of a teacher training program on teaching practices and school transformation. We carried out an exploratory case study involving eight public schools of the Community of Madrid. Twenty-nine teachers (including principals) and two counselors agreed to participate. The process involved discussion groups, in-depth interviews, questionnaires about the training received, and analysis of documents (reports, stories, and projects). The results found that there is a positive influence on how students live together, their learning, emotional intelligence, and social relationships.