This article presents a new attempt to estimate the size of the army and the population of Boiotia in the Hellenistic period. The calculation is based on an important type of epigraphic evidence in the region: conscription lists from the various cities of the Boiotian Confederacy, following a method initiated by Beloch. Confidence intervals are provided to estimate the age class of 20 in each city as well as whole districts where reliable data are available, and the population model is subsequently drawn from the work of contemporary statisticians. We reach a military potential of 11,000–14,500 men aged 20–49. This equates to a citizen population (including women and children) of 59,000–78,000 and to a total population of 75,000–115,000.