To ensure that they can participate in the Semantic Web, libraries need to prepare their legacy metadata for use as linked data. eXtensible Catalog (XC) software facilitates converting legacy library data into linked data using a platform that enables risk-free experimentation and that can be used to address problems with legacy metadata using batch services. The eXtensible Catalog also provides “lessons learned” regarding the conversion of legacy data to linked data by demonstrating what MARC metadata elements can be transformed to linked data, and helping to suggest priorities for the cleanup and enrichment of legacy data. Converting legacy metadata to linked data will require a team of experts, including MARC-based catalogers, specialists in other metadata schemas, software developers, and Semantic Web experts to design and test normalization/conversion algorithms, develop new schemas, and prepare individual records for automated conversion. Library software applications that do not depend upon linked data may currently have little incentive to enable its use. However, given recent advances in registering legacy library vocabularies, converting national library catalogs to linked data, and the availability of open source software such as XC to convert legacy data to linked data, libraries may soon find it difficult to justify continuing to create metadata that is not linked data compliant. The library community can now begin to propose smart practices for using linked data, and can encourage library system developers to implement linked data. XC is demonstrating that implementing linked data, and converting legacy library data to linked data, are indeed achievable.