Introduction: Coexistence in schools inevitably implies conflicts among peers, which can have a negative impact in both the students' well-being and their academic achievement. In this sense, the main objective of the present article is to introduce and describe the evaluation of the Training Program in Emotional Management Happy 8-12. This software focuses on the education of the pupils' emotional competences in order to solve conflicts in an assertive way. The program consists of 25 conflicts which students need to solve according to the management program of emotions developed by the Psychopedagogic Orientation Group (GROP). Method: The sample of the study consisted of 574 students of 5th and 6th grade of primary education. 301 of the participants were boys (52.4%) and 273 were girls (47.6%). Average age was 10.53, with a standard deviation of 0.662. The design employed in the present work was a quasi experimental design with pretest and posttest with a control group. The instruments and techniques used for the evaluation were: QDE, STAIC, CES, playground climate, anecdotic registration of conflict behaviours and academic performance. Results: Our results indicated that Happy 8-12 significantly improved the emotional competences of the students, reduced anxiety levels, and ameliorated the atmosphere in both the playground and in the class, noticeably augmenting the academic success. Conclusion: The results of this study show that training the management of emotions improves students' well-being at the same time that it acts as a preventive strategy for more severe disruptive behaviours, such as bullying. It also optimises the coexistence in the educative centres.