Speech and language competence in early childhood can influence academic achievement at school. The aim of this research was to examine longitudinal progress in literacy and numeracy achievement from age 8 through 12 years for children identified as typically developing or with speech and language concern (SLC) based on parent-reported concern about speech and language at ages 4–5 and 6–7 years. Participants were 4322 children in the K(indergarten) cohort and 4073 children in the B(irth) cohort of the Longitudinal Study of Australian Children (LSAC). The majority of children identified with SLC had not accessed speech-language pathology services. Linked data from national testing of literacy and numeracy achievement were analysed for the K cohort in Grades 3, 5, and 7, and for the B cohort in Grade 3. Cross-sectional analyses showed that children with SLC achieved lower scores for reading, writing, spelling, grammar, and numeracy at all assessment points than children with typical speech and language skills. Results for all children, however, were above the national minimum standard for each grade level. Longitudinal growth curve analyses showed no difference in the growth trajectories for literacy and numeracy test scores for children in the typically developing and SLC groups, suggesting that SLC children showed typical patterns of progression but did not catch up to the levels achieved by their typically developing peers.