This document is an ontology for the Material Culture Ethnography Metadata Schema (MCEMS), providing a formal definition of metadata elements and the schema’s structure. The schema is intended to be used by material culture-focused projects recording cultural practices, material knowledge and living heritage. It aims to facilitate the inclusion and preservation of metadata for project creating primarily digital recordings, documentation, datasets and archives and provides the potential to connect these to museum collections. Work on MCEMS began in 2019 by Nik Petek-Sargeant and continues to be developed under the auspices of the Endangered Material Knowledge Programme (EMKP), based at the British Museum and funded by Arcadia – a charitable fund by Lisbet Rausing and Peter Baldwin.