Clinical data registries are valuable tools that support evidence development, performance assessment, comparative effectiveness studies, and the adoption of new treatments into routine clinical practice. Although these registries do not have important information on long-term therapies or clinical events, administrative claims databases offer a potentially valuable complement. This article focuses on the regulatory and ethical considerations that arise from the use of registry data for research, including linkage of clinical and administrative data sets. (1) Are such activities primarily designed for quality assessment and improvement, research, or both, as this determines the appropriate ethical and regulatory standards? (2) Does the submission of data to a central registry, which may subsequently be linked to other data sources, require review by the institutional review board (IRB) of each participating organization? (3) What levels and mechanisms of IRB oversight are appropriate for the existence of a linked central data repository and the specific studies that may subsequently be developed using it? (4) Under what circumstances are waivers of informed consent and Health Insurance Portability and Accountability Act authorization required? (5) What are the requirements for a limited data set that would qualify a research activity as not involving human subjects and thus not subject to further IRB review? The approaches outlined in this article represent a local interpretation of the regulations in the context of several clinical data registry projects and focuses on a specific case study of the Society of Thoracic Surgeons National Database.