The importance of Beloch's Bevölkerung der griechisch-römischen Welt and its influence on subsequent research in ancient demography can hardly be overstated. This book represents the key-stone of all modern investigation on size, structure, and, to a certain extent, dynamics of ancient populations. It was the first overall scientific treatment of the subject and it is still unparalleled in its scope. An attempt at its critical evaluation is not just an historiographical exercise: we must come to terms with Beloch's Bevölkerung, because its detailed treatment of most of the topics concerning the population of the ancient world is at the root of all modern debates and controversies.