Purchasing power parity is central to exchange rate economics. This research review assesses a select set of classic papers on the subject. Individually and jointly, these studies have provoked heated debates on the validity of purchasing power parity, thereby making scholarly contributions towards analysing exchange rate puzzles. The findings have been profoundly influential in the conduct of monetary policy and business. This review provides a solid and succinct foundation for future research into the subject and is essential reference for scholars, researchers and policymakers alike.