Social – emotional competence is an important factor of person’s development. Peer relations are one of the indicators of social – emotional competence in which children with disabilities tend to show delays in comparison to their typically developed peers. Pupils spend most of their time in school setting where positive atmosphere, tolerance, acceptance of every pupil and friendship contribute to better development, academic achievements and quality of inclusion. This research wants to ascertain contribution of social – emotional development in area of peer relations on perception of inclusion. First aim of this research was to examine the effects of a 10 – week intervention on pupil’s social – emotional competence based on their as well as their teacher’s assessments. Second objective was to gain insight into experience of a pupil with disabilities in a classroom. Total number of 37 participants took part in this research, of which 19 was a part of an experimental group and 18 was a part of a control group and each group had a pupil with a disability. Data was collected before and after intervention through following questionnaires: Strengths and Difficulties Questionnaire, Child Interaction Scale, Peer Relations Questionnaire, Friendship Satisfaction Questionnaire and Perceptions of Inclusion Questionnaire for teacher and pupils and interview. Analysis of data was done using both quantitative and qualitative methods. Intervention was implemented with a goal of social – emotional development in area od peer relations of all the pupils in a classroom. It consisted of 10 workshops in duration of one school hour during 10 weeks. Results indicate in favour of intervention’s efficiency according to teacher’s report in area of decreasing aggressive interactions among pupils and improvement in perception of inclusion. Moreover, results showed positive, yet no statistically significant increase of social – emotional competence in area of problematic behaviours and peer relations according to teacher’s report, neither in pupil’s report regarding friendship satisfaction and perception of inclusion. Qualitative analysis showed that pupil with disabilities, after intervention, had friends who supported and helped him. This research shows that a ten-week intervention has a positive effect on improvement in social – emotional competence in area of peer relations and perception of inclusion as well as more positive experience of pupil with disabilities in classroom. Results encourage further research into effects of social – emotional learning, on raising quality of inclusion in Croatian schools.