There is continuing controversy regarding the optimal age at which children should begin formal schooling. In substantial number of countries in the world, the age of admission to compulsory schooling is six years, but it varies from four to seven, and some countries allow individual children to delay entry to school or to start school before compulsory school age (Bertram and Pascal, 2002; Sharp, 2002). In some cases, parents choose to delay their children’s entrance to school to allow them additional time to mature and thus acquire academic advantage, which is often referred to as “red-shirting”, and in some cases delayed entrance is recommended on the basis of readiness testing done prior to school entry (Zill et al., 1997). On the other hand, early admission refers to allowing children to begin schooling at an age younger than the officially approved school entrance age (Proctor et al., 1986). Among young children, small differences in age can lead to substantial differences in cognitive and emotional development, and hence affect their initial and/or later performance in school (Deming and Dynarsky, 2008). While some studies did not find significant relationship between school entrance age and academic achievement (e.g. DeMeis and Stearns, 1992), others show that within different grades older children tend to perform better academically than younger ones (e.g. Borg and Falzon, 1995). However, the size of achievement differences is seldom very large, and they are probably not persistent, although the age at which they disappear varies across studies (DeMeis and Stearns, 1992). In Croatia, children are obliged to enroll school if they reach the age of six by the cutoff date, which is April 1^st of the current year. Early admission is possible on parental request and with permission of expert committee, which assesses child’s psychophysical status and determines regular, early or delayed entrance to school. The aim of this study is to examine the differences in achievement in various subject areas among pupils who were younger or older at the time they entered school. These differences were examined among pupils who attended fourth or eight grade of Croatian primary schools at the time of testing. Pupils within these grades had received the same length of formal schooling, namely four or eight years.

Bertram, T., Pascal, C. (2002). Early Years Education: An International Perspective. London: Qualification and Curriculum Authority. Borg, M. G., Falzon, J. M. (1995). Birth Date and Sex Effects on the Scholastic Attainment of Primary School Children: A Cross-sectional Study. British Educational Research Journal, 21 (1), 61-74. DeMeis, J. L., Stearns, E. S. (1992). Relationship of School Entrance Age to Academic and Social Performance. Journal of Educational Research, 86 (1), 20-27. Deming, D., Dynarski, S. (2008). The Lengthening of Childhood. Journal of Economic Perspectives, 22 (3), 71-92. Proctor, T. B., Black, K. N., Feldhusen, J. F. (1986). Early Admission of Selected Children to Elementary School: A review of research literature. Journal of Educational Research, 80 (2), 70-76. Sharp, C. (2002). School Starting Age: European Policy and Recent Research. Paper presented at the LGA Seminar “When Should Our Children Start School?”, LGA Conference Centre, Smith Square, London, November 1st 2002. Zill, N., Spencer Loomis, L., West, J. (1997). The Elementary School Performance and Adjustment of Children who Enter Kindergarten Late or Repeat Kindergarten: Findings from National Surveys (NCES Statistical Analysis Report 98-097). Washington: U.S. Department of Education, National Center for Education Statistics.