The Library of Congress Medium of Performance Thesaurus (LCMPT) and the music portions of the Library of Congress Genre/Form Terms for Library and Archival Materials (LCGFT) are long-anticipated products in a history of problem-solving approaches toward faceted access to music resources. MLA’s Cataloging and Metadata Committee has collaborated with the Library of Congress for the past several years in a multiphase endeavor to design and build out these new vocabularies. Implementation within the Anglo-American music cataloging community began in 2014, and retrospective implementation (the programmatic assignment of faceted terms to legacy metadata) is currently being studied and pursued.