The Entity Metadata Management API (EMM API) is an effort with the LD4 community to define a specification for communicating changes to linked data entity datasets so that data consumers are aware of new, updated, and deprecated entities as the dataset evolves over time. Understanding these types of changes is critical for a number of use cases including local caching of labels and caching of full datasets. The specification builds on the widely adopted W3C ActivityStreams specification with usage patterns appropriate for entity datasets. This presentation will provide an overview of the use cases and specification. We will also share examples of early implementations (including the Library of Congress, e.g. id.loc.gov subjects), demonstrating the specification is ready for adoption.