This article seeks to count late-antique clergy and assess their workload. It estimates the number of clerics, and particularly presbyters, in Christian communities of various sizes, and investigates how and why the ratio of clerics to laypersons changed over time. First, by examining the situation in the city of Rome, it demonstrates that the growth in the ranks of the presbyters from the third to the fifth century was slow, and argues that this resulted from the competing interests of the bishops, lay congregation, rich donors, and above all the middle clergy. It is the last group who were reluctant to raise their number as this had a negative impact on their income. The results of this phenomenon can also be seen in other big sees of Christendom, in which, in Late Antiquity, there was one presbyter per several thousand laypersons. Interestingly, in smaller towns, this ratio was significantly lower, and in the countryside, it remained in the lower hundreds. Second, this article shows how the changing ratio of clerics to laypersons affected the level of professionalization of the former. In the big cities, the ecclesiastical duties of presbyters who served in a growing community were getting heavier. This turned the presbyters into full-time religious ministers, at the same time making them even more dependent on ecclesiastical income. In the towns and villages, however, the pattern was different. In the places in which one presbyter served a very small community, his job was less time-consuming but also brought him less income. In consequence, rural presbyters had to support their families through craft work, commerce, or farming, and they had time for this.