It’s fabulously expensive, but looks fascinating: Fasti Sacerdotum: A Prosopography of Pagan, Jewish, and Christian Religious Officials in the City of Rome, 300 BC to AD 499. You’ll find it reviewed in BMCR.

Scholars of ancient Rome will be delighted that Rüpke’s monumental work, Fasti Sacerdotum, has been translated into English and thus become accessible to a wider readership … For those unfamiliar with the German edition, its aim was to construct annual lists for the city of Rome of attested priests, cult officials and followers from 300 BCE to 499 CE, lists that included not just pagan priests but also the officials from Jewish and Christian groups. The work falls into two main parts: a compilation of annual lists of priests and religious functionaries and a set of alphabetically arranged individual biographies. Understandably, the whole work was 14 years in the making and required a team of assistants.

The idea of the compiling the biographies is to personalize the religious history of the city of Rome through a biographical approach. Rüpke intends the work to be an instrument for researchers in the field of religious and cultural history. At all times he is aware of the limited nature of the source material at our disposal, which is derived largely from inscriptions.