Increasingly, modern-day software systems are being built by combining externally-developed software components with application-specific code. For such systems, existing program-analysis-based software-engineering techniques may not directly apply, due to lack of information about components. To address this problem, the use of component metadata has been proposed. Component metadata are metadata and metamethods provided with components, that retrieve or calculate information about those components. In particular, two component-metadata-based approaches for regression test selection are described: one using code-based component metadata and the other using specification-based component metadata. The results of empirical studies that illustrate the potential of these techniques to provide savings in re-testing effort are provided.