Institution for early and preschool upbringing and education takes care for preschool children and one of their most important roles is to prepare children for school. Quality preparation greatly influences the child’s adaptation to the specific requirements that the school places on a child. Chronological age, as one of the criteria for enrolment of a child in the first grade of elementary school, refers to children who, by April 1 of the current year, have reached the age of 6. Since each child is an individual who is developing at his own pace, this criterion is not entirely reliable. Therefore, the criterion of psycho-physical readiness stands out as an important constituent in assessing the child’s readiness for school. In order to examine the readiness for the school, one should first get acquainted with the very concept of school readiness and determine what it implies. The aim of this paper is to explain and explore the psycho-physical readiness of pre-school children who are attending a regular pre-school education program. For the purpose of this research, a maturity assessment questionnaire, consisting of 10 evaluation areas, was used. The results showed that out of 53 children, 6 of them did not show enough maturity for the school, and it was recommended for them to postpone school enrolment in that pedagogical year.