Public debt dynamics are a key determinant of a country’s macroeconomic environment and private investment climate. The objective of this paper is to provide a better understanding of public debt dynamics for market access countries for the last 10 plus years. It breaks down changes in public debt-to-GDP ratios into components attributable to primary fiscal deficits, real GDP growth, real interest rates, the capital gain/loss on foreign currency denominated debt as result of exchange rate changes and fiscal costs associated with contingent liabilities such as bank bailouts. The analysis draws upon 31 market access countries (MACs), for 15 of which detailed case studies are done. When interpreting the public debt decompositions, it is important to remember that this is to a large extent a mechanical accounting exercise. In particular, it ignores the fact that all the factors contributing to the changes in the level of debt are simultaneously determined and influence each other. Hence, the case studies attempt to link changes in debt-to-GDP ratios to episodes of marked policy change or structural factors. We conclude by extracting lessons from the aggregate debt analysis and individual country debt decompositions.