Prices and wages are the social phenomena most susceptible of objective statistical record over long periods of time. They reflect and measure the influence of changes in population, in supply of precious metals, in industrial structure and agricultural methods, in trade and transport, in consumption and in the technical arts. Forming part of publications of the International Committee on Price History, this is Volume I of data from the twelfth to the nineteenth century. It was originally published in 1939 and almost the entire stock was destroyed during an air-raid. The present volume is a facsimile of that edition. This volume looks at the Mercantile era.