Sentara Healthcare is a $3 billion conglomerate that includes hospitals, clinics, physician networks, insurance companies, research centers, etc. It offers thousands of services to over two million patients. It is a very complex business. Always on the cutting edge of applying information systems technology to improving healthcare delivery, Sentara engaged Semantic Arts to build the first comprehensive model of a healthcare delivery system. After an exhaustive analysis of the thousands of interrelated processes required to run a complex healthcare business, the Sentara Healthcare Enterprise Ontology included only 1,276 classes and 397 properties. We are currently applying the ontology as a common denominator to align internal and external data without needing to make any significant increases or structural changes to the definitional schema. These are examples of how large, complex organizations with hundreds of thousands of elements in their collective schemas can create integrated models of reasonable coverage and fidelity with around 1,000 – 2,000 concepts. By taking a semantic approach to building these simple, elegant and powerful schemas, we have found a way to reduce complexity.