Schooling for Sustainability: Disaggregating the Effects of Primary, Secondary, and Tertiary Education on Sustainable Development in the Global South

SDG progress falters when education is treated as a monolith; aligning each schooling rung with its strongest payoff is vital to balance growth, equity, and climate action. We examine how primary, secondary, and tertiary education relate to economic (GDP per capita), social (Gini index), and environmental (CO 2 per capita) outcomes in 60 developing countries, 1996–2022. We estimate short‐ and long‐run effects with CS‐ARDL, accounting for common shocks and heterogeneity, and explore distributional heterogeneity with MMQR. Findings are level‐specific: primary strongly reduces inequality; secondary is the principal driver of GDP; tertiary yields the largest long‐run environmental gains via innovation and governance. First, substituting the HDI‐education index preserves the education–growth link but reveals trade‐offs: higher attainment associates with wider inequality and higher emissions where equity and green policies lag. CCEMG income subgroups show that in lower‐income settings, tertiary lowers inequality but raises emissions, while in higher‐income peers, secondary and tertiary lift GDP. CCEMG institutional‐strength estimates indicate that where institutions are weak, secondary boosts GDP, tertiary raises emissions, and primary aligns with higher inequality; where institutions are strong, benefits are more balanced with lower environmental costs. Country heterogeneity is evidenced by clusters of secondary/tertiary dominance and primary‐dominant belts with lower composite scores. Policy: target investments to pillar‐specific strengths and pair education with governance and green‐growth reforms to convert human capital into inclusive, low‐carbon development.