The OCLC CONTENTdm Metadata Working Group was formed in response to research demonstrating the need for guidelines and best practices for creating quality Dublin Core metadata, which is useful to the primary user community and “shareable” outside of the local context. The CONTENTdm Metadata Working Group has worked since August 2009 in a test environment to develop best practices for creating Dublin Core metadata in CONTENTdm and mapping to MARC to share in WorldCat via the WorldCat Digital Collection Gateway, a self-service OAI harvesting tool. The best practice document identifies 12 core elements and four recommended elements, and provides guidelines for field content standardization and mapping to other metadata standards. Concerns such as adherence to the Dublin Core one-to-one principle regarding the recording of original and digital dates and publishers are also discussed, along with recommendations for configuring metadata for the Digital Collection Gateway to increase the shareability of metadata.