Descriptive Cataloging of Rare Materials (RDA Edition) (DCRMR) is a rare materials cataloging standard aligned with the official RDA Toolkit. DCRMR is informed by core principles of community and sustainability while employing open-source publication models and infrastructure. The RBMS RDA Editorial Group, composed of rare materials catalogers actively working in the field, is responsible for developing and maintaining DCRMR. This article discusses predecessor rare materials cataloging standards that led to the development of DCRMR, the principles and constraints that shaped DCRMR from its initial inception to eventual release, the method and technical tools used to achieve the RBMS RDA Editorial Group’s outcomes, and future directions for development.