Abstract
This article describes the progress of the Digital Library Federation's Aquifer Metadata Working Group and demonstrates a model for the construction, application, and testing of collaboratively developed best practices for sharing metadata in the digital library environment. We set the metadata aggregation context in which the Aquifer initiative began, describe the development of a set of implementation guidelines for shareable Metadata Object Description Schema (MODS) records and their supporting documentation and tools, and discuss how this work has contributed to the understanding of what features metadata describing primary source and humanities-based resources needs in order to support scholarly use. We end with a summary of future efforts for the Aquifer initiative, and how its lessons can be applied in other metadata harvesting environments.