A high level of quality of work in the context of early and preschool education implies care and achieving a high level of children's well-being. This is particularly important in the framework of two aspects: developmental tasks such as the development of attachment in children, and specific and developmentally demanding situations such as situations of transition from family to kindergarten. With this in mind, their levels and relationships are analysed in this paper. The aim of the research was to determine the relationship between attachment, adaptation, and children's well-being (satisfaction during adaptation, mother's sensitivity, child's temperament, and relationship with educators), and socio-demographic variables. After obtaining permits and consent to conduct research, the same was conducted on a sample of 11 educators and 129 children in kindergartens in the Primorje-Gorski Kotar county during 2022. The variables: children's temperament, children's attachment (avoidance, support, mother-child closeness, and rejection), quality of transition and adaptation of children in kindergarten with four questions, mothers' sensitivity, and the relationship between educators and children (closeness and conflict). As assumed, the results of the research showed the highest prevalence of secure attachment and adequate adaptation in children, a higher level of satisfaction during adaptation, the existence of higher levels of maternal sensitivity, higher levels of sociability and activity, lower emotionality in the framework of children's temperament tests, and the existence of close relationships between educators and children. The existence of a connection between certain variables of attachment, adaptation, and well-being (satisfaction during adaptation, mother's sensitivity, child's temperament and relationship between educators and children), socio-demographic variables of educators and kindergarten characteristics, and socio-demographic variables of children and their parents was also determined. The established findings of the research confirmed the findings of previous research and indicated the importance of the examined variables in the quality of the transition and adaptation of children from the family to the kindergarten. Therefore, the contribution of this work is visible both in the field of empirical research and useful implications for strengthening the quality of educational practice during the transition and adaptation in kindergarten.