The purpose of our research is to determine emotional and behavioural modelling in an emotionally safe environment in a group of kindergarten preschoolers, following the application of an innovative curriculum project, designed and implemented for the first time, Educational Program for the training and development of social and emotional skills (DeCo-S.E.). Eighteen teachers, involved in the research, were divided into two samples: the experimental group (EG) consisting of 10 preschool teachers who were trained to take up the DeCo-S.E. program, and the control group (GC) including eight preschool teachers who applied the classic educational strategies. The DeCo–S.E. program is aimed at developing social and emotional skills (emotion identification, frustration tolerance), reducing behavior problems, and solving problems with peers as part of the training process. The study also included 142 children in their last year at kindergarten, aged X ± SD 5.87 ± 2.87 years old, divided into two groups: the EG consisting of 74 children to whom the experimental program was implemented and the GC comprising 72 children who did not take part in the training program. In the present study, we applied only the Preschool and Kindergarten Behavior Scales for Teachers (PKBS-2) questionnaire to children in the pre- and post-experimental phases. The results were processed with the statistical software SPSS 22. The analysis of the scores of the questionnaire applied to the children highlighted a significant improvement in EG on both scales. The study reveals the effectiveness of the Development of social and emotional skills programs in preschool children has proven its effectiveness by reducing undesirable/maladaptive behaviours and positively developing socio-emotional skills in preschool children.