Diagnostic radiologists generally produce unstructured information in the form of images and narrative text reports. Although designed for human consumption, radiologic reports contain a wealth of information that could be valuable for clinical care, research, and quality improvement if that information could be extracted by automated systems. Unfortunately, the lack of structure in radiologic reports limits the ability of information systems to share information easily with other systems. A common data element (CDE)-a unit of information used in a shared, predefined fashion-can improve the ability to exchange information seamlessly among information systems. In this article, a model and a repository of radiologic CDEs is described, and three important applications are highlighted. CDEs can help advance radiologic practice, research, and performance improvement, and thus, it is crucial that CDEs be adopted widely in radiologic information systems. © RSNA, 2016.