The Hydra Archivists Interest Group is composed of archivists working at institutions affiliated with Project Hydra and engaged in repository development using that community’s suite of tools. Archivists at these institutions meet regularly to discuss ways in which they can advance archival technology needs through better communication and understanding of software development activities. During this three hour working meeting, we will discuss data modeling -- what it is, why archivists should care -- and then start a conversation around developing a data model for archives. This meeting is co-sponsored by TS-DACS, and is open to anyone interested in the technical standards that inform archival description, including not just EAD, DACS, and EAC-CPF, but emerging standards like the Portland Common Data Model and the work of ICA’s Expert Group on Archival Description. We welcome all who are interested, but our room size is limited to 60. We also respectfully seek attendees who are prepared to participate, since a significant portion of this meeting will be composed of break-out discussions and activities.