Based on longitudinal data (n = 338) from the German National Educational Panel Study (NEPS) competence development (mathematics and language) of three groups with different mathematical preconditions (+/- 1 SD) were compared between age 4 to 10. Groups were composed by first measurement of mathematical achievement in pre-school age (5/6 years). First, further mathematical development of the groups was investigated up to grade 4 of primary school. Second, group differences in grammar and vocabulary between pre-school and primary school children were explored. Results show a consistent development of mathematical competence in all three groups from pre-school age until 4th grade. Children with low mathematical achievement measured in pre-school age were not able to overcome these deficits during primary school. In contrast, vocabulary development of the three groups varies over time: Within the group with low mathematical achievement measured in pre-school age their similarly weak vocabulary skills caught up with the vocabulary achievements of the other two groups during the following school years. For grammar, the small group-related differences in pre-school become even more pronounced in grade 1. The results contribute to a better understanding of the complex dynamic interrelationship between the development of linguistical and mathematical skills in K-4 and are discussed with respect to the importance of early mathematical promotion.