Within the fields of human performance technology (HPT), human resources management (HRM), and management in general, performance measurement is not only foundational but considered necessary at all phases in the process of HPT. In HPT in particular, there is substantial advice literature on what measurement is, why it is essential, and (at a technical level) how to do it. However, there is practically no critical discussion of how measurement is made possible, how it is done, and what can be done with measures once they are created. With the goal of beginning to fill this void, this article draws from a multiyear ethnography in call center organizations to report an ethnostatistical analysis of these aspects of performance measurement. Following this analysis, implications for the present and future of HPT are discussed.