Book excerpt: Avedis Donabedian's name is synonymous with quality of medical care. He unraveled the mystery behind the concept by defining it in clear operational terms and provided detailed blueprints for both its measurement(known as quality assessment) and its improvement(known as quality assurance). Many before him claimed that quality couldn't be defined in concrete objective terms. He demonstrated that quality is an attribte of a system which he called structure, a set of organized activities whihc he called process, and an outcome which results from both. In this book Donabedian tells the full story of quality assessment and assurance in simple, clear terms. He defines the meaning of quality, explicates its components, and provides clear and systematic guides to its assessment and enhancement. His style is lucid, succinct, systematic and yet personal, almost conversational.