This paper provides an overview of specifications and standards for metadata relating to learning materials. It is structured to present first the currently established metadata schemas in use today (specifically the IEEE LOM and Dublin Core metadata), then to examine current developments and activities before looking at what might be the future challenges. The examination of current developments and activities highlights the increasingly recognized importance of metadata schema that describe what have in the past been thought of as secondary aspects of learning materials (for example who uses them and what for), and the importance of alternative approaches to structured metadata for resource description.