Initiated in 2021, the University of Washington Libraries have committed to using LRM/RDA/RDF (RDA as Linked Data) to represent RDA description sets. While LRM/RDA/RDF has not been widely adopted and few test datasets exist, this could change rapidly if libraries transform legacy MARC data to LRM/RDA/RDF. As they near completion of Phase 1 of the project, presenters will describe a groundbreaking mapping and conversion project between the MARC21 bibliographic standard and LRM/RDA/RDF. In addition to describing the cross-organizational team, the presentation summarizes the scope and strategy of the first phase of the project, describes key discussions, highlights important decisions, and shares project workflows. Challenges with aggregate works and expressions, ambiguously-described entities, reproduction manifestations, inconsistent cataloging practices, and more are discussed. Advance releases of project deliverables are shared ahead of their anticipated official publication at the end of 2024, including mappings in .csv format, XSLT transformation code, and sample transformation data in the original MARC21 format and the resulting LRM/RDA/RDF which will be published in a Wikibase Cloud instance. Project members hope that Phase 2 of the project will address entity reconciliation and identity management as well as more complex aggregate types. More information about the open project can be found in the following GitHub repository: https://github.com/uwlib-cams/MARC2RDA