This research examined preschool children's social-emotional problems and school adjustment processes in different countries. Furthermore, this study compared the school adjustment programs and the teachers' solutions in other countries. A qualitative research method and case study design were used. The sample group consisted of 21 preschool teachers from Turkey, Italy, Lithuania, Hungary and Northern Ireland within the scope of the Erasmus+ project 'Developing Social and Emotional Skills in Early Childhood' (SESDECE). A semi-structured interview form was used to obtain the research data. According to the data, it was revealed that separation anxiety, attachment disorder and poor communication with peers were the most common problems in the school adjustment process in all countries. It was determined that teachers in Turkey, Hungary, Lithuania and Northern Ireland used different adjustment programs and solutions during the adaptation. In contrast, teachers in Italy did not use a fixed adjustment program but enriched the first week's programs with activities such as meeting-adjustment activities. Teachers in all countries stated that school administrations support the process, but families should be more involved and a unique adjustment program should be applied to families.