GDP volatility has become a fundamental development concern given the established negative link between short-term fluctuations and long-term economic growth. This paper analyses the determinants of GDP fluctuations in selected South Asian countries, examining the structural, external, and policy factors that generate macroeconomic instability in the region. Using panel econometric techniques suited to the small-N, large-T structure of the dataset, the study identifies the relative contributions of trade openness, inflation, financial development, and structural characteristics to observed GDP volatility. Findings provide an empirical basis for macroeconomic policy design aimed at reducing growth-damaging volatility in South Asian developing economies.