Background: Research on academic development has mainly focused on early time periods with less attention on individual differences in development in the later school years. Methods: To improve our knowledge of how students develop academically during later school years, this study used a multivariate growth model to investigate the developmental trajectories of literacy and math skills in a sample of Australian students in fifth through ninth grades (n = 114). Results: Students progressed at greater average rates in math from primary to secondary school than in literacy. Both literacy and math skills showed significant individual differences in growth rate at Grade 9. There was no evidence of an association between change in math and change in literacy. Primary school socioeconomic status was not a statistically significant predictor of inter-individual differences in the development of either literacy or math. Conclusions: These results, taken together, suggest that both domain-general and domain-specific influences act on the development of these academic skills.