This article describes a research project about the development of early numeracy in 5- to 7-year-old Flemish children compared to their Dutch peers. A group of Flemish children was tested 3 times by means of a slightly adapted Flemish version of the Utrecht Early Numeracy Test, and their results were compared to the development of those of a comparable group of Dutch children. The first and the second assessment took place, respectively, at the middle and at the end of the last year of preprimary education, and the third assessment at the middle of the first year of primary education. The results indicate that the Early Numeracy Test is a moderately reliable and construct valid instrument to assess the general early numeracy. At the time of the first assessment Flemish children scored worse on the test than their Dutch peers. However, they showed a faster progression between the first and the third assessment, resulting in a catch up with their Dutch peers at the third assessment. The results are interpreted in terms of differences in the goals, the content, and the organization of preprimary and primary school mathematics education in both countries.