Background: This article presents the Afrikaans translation of an originally German diagnostic test for early number concept development. The process of 'importing' a test to South Africa by considering linguistic-, functional-, cultural and metric equivalence is outlined. A theoretical model describes five levels of young children's hierarchical number concept development which collectively contribute to early mathematical understanding. The five-level hierarchical structure has previously been confirmed by testing the theoretical model in a one-dimensional Rasch analysis in Germany. Aim: The current study aimed to determine whether the individual items, allocated to test the concepts of each level of the Afrikaans translation of the diagnostic test, confirm the hierarchical structure of the theoretical model. Setting: A Rasch analysis indicated that the model was fit for the Afrikaans translation. A sample of 165 Afrikaans-speaking grade one children was tested in six Afrikaans medium primary schools in Gauteng. Methods: Analysis of fit values, person and item reliability and a person-item map was used as part of a Rasch analysis. Results: The theoretical model of hierarchical number concept development holds for the Afrikaans MARKO-D. Five levels were clearly distinguishable on a Write map and the individual items tested the concepts according to the levels of the theoretical model. Conclusion: The Afrikaans MARKO-D can now successfully be used to describe young Afrikaans children's number concept development. A five-level theoretical model is a useful tool for teachers using the MARKO-D to assess young children's numerical competence.