The paper describes school readiness in grades 1–3, according to initial entry age to school. Authors approach contemporary understanding of literacy development from the angle of Vygotsky’s view on cultural-historical psychology. From this perspective reading and writing are seen as two manifestations of a single higher mental function – written speech. During the initial stages of school these skills can be regarded as main indicators for the interactional aspect of school readiness. 314 pupils from grades 1–3 were tested to identify differences between those starting school aged 6- and as 7-year-olds. The Literacy Assessment Battery and Coloured Raven’s Progressive Matrices were the instruments chosen. Results showed no differences in level of written speech between any of these groups. A plausible explanation for this similarity may be found in higher levels of fluid intelligence and from parents’ education. This suggests that Polish children starting school at 6 years of age before 2015 were recruited from an elite group.