In this paperwork there is a theoretical consideration of psychological construct of children's rediness for school. It involves an examination of the physical, psychomotor, emotional, intellectual, perceptional and social aspects of child's development and prereading skills , communication skills and premath skills. In a study conducted in this paperwork, we investigated the process of evaluating the readiness of children for the enrollment in the first grade in three primary schools. The research results show that the proceedings in all three schools are carried out in accordance with the rules of Procedure of determining the psychological and physical condition of the child, students and the composition of expert committees. Time and place of the procedure is somewhat different in the three examined schools, as the number of professions and members of the Expert Commission for determining the psychological and physical condition of children before entering the first grade. Communication as an essential part of the assessment process is adequate as between the members of the Expert Committee and children, and between members of the Commission and the parents. All three schools have a good cooperation with pre-school institutions which children attended until the enrollment in the first grade of elementary school.