The XML-based Clinical Document Architecture (CDA) for document exchange defines a three-level document architecture with each higher level adding more specificity to the markup of the document. Such a layered architecture also meets the requirement for semantic processing of hierarchically structured clinical documents. The CDA supports shared care between hospital-based and community-based physicians, knowledge integration by permitting external links to other documents, and outcomes research through the capture of discrete and coded clinical data. The research reported in this paper has lead to the successful prototyping of a CDA-based Structured Discharge Summary system. Structured discharge summaries are used to move clinical information from the clinical environment, such as the geriatrics department of a hospital, to the community environment of family practice. They are an education, communication, research, and administration tool in the Departments of Medicine and Family Medicine and at the Queen Elizabeth II Health Sciences Centre.