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 long-term memory. Over the past 40 years, research on how students aged 6 to 20 acquire IRTH has yielded varied and sometimes contradictory conclusions about this process’ timeline and underlying mechanisms. This paper aims to synthesize the evidence and critically examine potential reasons for the heterogeneity in findings. To this end, three approaches were applied. First, a Bayesian meta-analysis of 60 effect sizes from 16 studies, reported in 13 articles, revealed a medium difference in IRTH sensitivity between younger and older participants (d = 0.57,95% CrI [0.37,0.77]). Second, a Bayesian network analysis indicated that tonal understanding continues to develop throughout school years into adulthood, challenging models suggesting that tonal development concludes by age 7 or 9. Third, a model comparison analysis based on cross-sectional data from a single study revealed a non-linear growth dynamic with a larger increase during adolescence as the best model solution to describe the relationship between sensitivity and age. We also examined the considerable heterogeneity observed within and between studies, particularly how task-specific features of the operationalizations might account for these differences. These findings contribute to the development of theoretical models about music-related skill acquisition and suggest directions for future research.