The purpose of this article is to review metadata issues identified in recent research carried out in Scotland on services based on metadata aggregation via OAI-PMH, and to examine the role of collection-level description in managing ingest to harvested repositories, subsequent harvesting by secondary aggregators, and the contextualisation of institutional and aggregated repositories in the wider information retrieval environment. The paper reviews the output of several projects involving institutional repositories and collection-level description in Scotland. Collection-level description is a useful tool for aggregator services, but further work is required to accommodate information about the manipulation of metadata sets. Communities need to consider how best to incorporate structured collection information within the OAI-PMH for their specific purposes. The paper shows the importance of recent developments in collection description metadata for implementors of OAI-PMH services, building on the simple placeholders for such metadata allowed by the protocol.