Statistics about the Catholic population of the United States have frequently been used for political and ideological purposes, at the same time as they have figured prominently in discussions about the disaffiliation of Catholics from the institutional church. But how are the most commonly cited statistics generated, and to what extent are they reliable? This article reports the results of a new, qualitative study of the procedures by which a randomly selected group of Catholic dioceses and archdioceses in the U.S. obtain and publish their population statistics. In addition to assessing the reliability of the procedures used, this essay also reflects on the theological, ecclesial, and political dimensions of the processes of data collection and reporting. Despite the aspirations of the church workers interviewed, most do not believe that the methods at their disposal permit them to report with accuracy important statistics about the populations of their parishes and dioceses. Factors like the choice of statistical methods, unforeseen events in particular dioceses, and the presence of intra-ecclesial incentives to report both higher and lower statistics all reveal that to count the Catholic population is to engage, wittingly or unwittingly, in a theological and ecclesio-political act.