The size of a country's population became a political topic only during the Early Modern Age. Around the year 1600 political theorists in Germany began to expound on an idea that stemmed originally from Italy, namely, that the state must pay attention to the development patterns of its own population. This call for an expansive population policy was thus sounded even before the devastations of the 30-Year War and became established outside of learned circles in the course of the 17th century. It formed the basis of what came to be known as cameralism. Finally, this movement developed into the populationism of the 18th century, which advocated increasing the size of the population at all costs and measured the success of all politics in the demographic ramifications. In this work Justus Nipperdey reflects for the first time on the rise of this concept of population politics in 16th-century Italy, the adoption thereof by political theorists in other parts of Europe and its transition from learned Latin political works to German treatises.