The thesis deals with the issues of internalizing behaviour problems of early childhood and preschool children. The first part of the thesis defines the behaviour and importance of emotional and social development of the child. Furthermore, definition of behavioural problems is presented as well as the method of assessing the children’s behaviour and description of the concept and types of internalizing behavior problems. The second part of the thesis describes a survey conducted on a sample of 111 educators in Istria County. Based on the set hypotheses and the obtained results, it can be concluded that educators are mostly insecure about their knowledge of internalizing problems, that very few educators are regularly educated in this area and that they are considered predominantly incompetent. Educators estimate that a child with internalizing behavior problems has different adaptation difficulties in the kindergarten group, almost half of respondents believe that internalizing behavior problems occur equally in children of both sexes and that they only partially agree that children with developmental difficulties are more likely to manifest internalizing behavior problems than children with normal development.