METS is an XML document format intended for the encoding of complex objects within digital libraries. It provides the means to record all of the descriptive, administrative, structural and behavioral metadata needed to manage and provide access to complex digital content. While it was designed to promote interoperability of digital content between digital library systems and contribute to the preservation of digital library materials, a variety of practical barriers to achieving these goals remain. However, many of these obstacles are shared by other communities of practice, such as the eLearning community working on the IMS content packaging standards and the MPEG-21 community, and the digital library community faces a unique opportunity at the moment to work closely with others to try to improve the interoperability of our content not only with our own repository systems, but those being used by others.