Each preschool is obliged to prepare children to start school education, which means it should equip them with such skills and competencies that determine their readiness to start learning at school, in other words, school maturity. The aim of this study was to determine the level of emotions, feelings and social-emotional behaviours of six-year-old children at the school threshold as determinants of their positive adaptation to school conditions. Other aspects of school maturity, such as cognitive or physical were not the subject of scientific exploration. The main technique applied to collect empirical material was passive pedagogical observation. Data were collected with the use of a pedagogical observation sheet during children's stay in preschools, at the time of their play and free activity. It contained questions about visible manifestations of particular 28 emotions, feelings and social-emotional behaviours.