One response to the current crisis in medicine -- indicated by large variations in practice and skyrocketing costs -- has been a call for the rationalizing of medical practice through decision-support techniques. These tools, which include protocols, decision analysis, and expert systems, have generated much debate. Advocates argue that the tools will make medical practice more rational, uniform, and efficient: that they will transform the "art" of medical work into a "science." Critics within medicine, as well as those in philosophy and science studies, question the feasibility and desirability of the tools. They argue that formal tools cannot and should not supplant humans in most real-life tasks. Marc Berg takes the issues raised by advocates and critics as points of departure for investigation, rather than as positions to choose from. Drawing on insights and methodologies from science and technology studies, he attempts to understand what "rationalizing medical practices" means: what these tools do and how they work in concrete medical practices. Rather than take a stand for or against decision-support techniques, he shows how medical practices are transformed through these tools; this helps the reader to see what is gained and what is lost. The book investigates how new discourses on medical work and its problems are linked to the development of these tools, and it studies the construction of several individual technologies. It looks at what medical work consists of and how these new technologies figure in and transform the work. Although the book focuses on decision-support techniques in the field of medicine, the issues raised are relevant wherever rationalizing techniques are being debated or constructed. Touching upon broader issues of standardization, universality, localization, and the politics of technology, the book addresses core problems in medical sociology, technology studies, and tool design.