Understanding the relationships between different pitches as a form of tonality is a key element of listening skills in Western tonal music. Tonal hierarchies (i.e., the genre-dependent differing prominence of tones) are reflected in internal representations of tonal hierarchies (IRTH) in the long-term memory. This meta-analysis quantified IRTH development as a function of age in primary and secondary school students. We identified eligible articles following a systematic and comprehensive literature search strategy suggested by What Works Clearinghouse (2020). Based on an initial h=3,635 hits, we aggregated i=13 articles reporting j=16 studies with y=47 observed effect sizes. A Bayesian three-level hierarchical model showed a median correlation of r=0.41,95%CrI [.30,.50] between age and IRTH development. Consequently, the correlation between age and IRTH development is likely to be positive and of a medium-to-large size. Substantial variance was found between (τ_1=.18,95%CrI [.02,.33]) and within studies (τ_2=.26,95%CrI [.18,.34]), each of which was attributed to a single study. The main outcome suggests that tonal development is not finished when children start school and school years are important for tonal development.