This paper investigates why the post-COVID inflation surge, though globally synchronized, led to widely divergent outcomes across countries. Using cross-country regressions for 130 economies and local projections methods for 70 advanced and emerging markets, we analyze the structural, institutional, and policy determinants of post-pandemic inflation dynamics. The results indicate that historical inflation and the scale of domestic energy price shocks account for most of the cross-country variation in cumulative post-COVID inflation. In contrast, many frequently cited country-specific, macroeconomic fundamentals and institutional features exhibit limited power to explain cross-country variation. The association between post-COVID inflation and domestic policy responses is also weak, although endogeneity complicates a clear causal interpretation. The analysis further reveals that pass-through from energy prices to headline inflation intensified markedly in the post-COVID period, particularly in emerging markets, in non-inflation-targeting regimes, and in countries that did not expand fossil fuel subsidies. These findings highlight the asymmetric transmission of supply shocks and underscore the importance of credibility, historical inflation experience, and energy policy design in shaping inflation persistence. Strengthening central bank credibility and anchoring expectations may be essential to bolster resilience against future global supply disruptions.