Prologue:In Evita, Andrew Lloyd Webber and Tim Rice wrote: Politics, the Art of the Possible. To those of us in the operations research community, we postulate: Operations Research, the Science of Better -(i.e. better processes, better systems and better decisions). Using our own and other scientific, engineering, mathematical, and social sciences methodologies, operations researchers help decision makers make better decisions; decisions leading to improvements: greater quality, lower costs, greater revenues, better access, better scheduling, lower risks, more satisfaction -with the goal of always striving for the best or optimal decisions.1389-1995/09/$17.00 2009 -IOS Press and the authors. All rights reserved 242 W.P. Pierskalla / Operations research sectors, health-care sectors, and virtually every other sector in which strategic or operational decisions must be made to improve planning, performance and outcomes.Most operations research applications involve analyzing complex situations. The approach taken begins by looking at the complex situation from a systems perspective. Inside the system, processes are diagrammed and analyzed and a model is constructed based on the flows of people, products, services, technologies and information. Using this structure, the approach models the objectives desired to be achieved, the fixed and variable constraints on the system, all available options for decisions, evaluation of all possible outcomes, estimation of risks and bringing to bear the latest tools and techniques leading to improved or optimal decisions on system operation and outcomes. In most applications, it is frequently the case that multiple objectives such as to improve quality, lower costs, improve access and improve satisfaction are simultaneously achieved. In some cases, multiple objectives trade-off against one another and the decision maker has to weigh these objectives and choose among them. In this latter situation, operations research also provides decision analytic methodologies for optimally weighing and choosing among competing objectives.Because this book is about "Engineering the Health Care System", this chapter will be devoted to operations research applications in health care delivery with mentions of theory and methodologies as appropriate. We have space to cover only some of the applications from the thousands available but hope to do so with enough breadth of topic and depth of description to give a flavor for the capabilities of operations research in developing better or best solutions for many complex health care issues. If one wishes to have a brief introduction to the theory and methodologies mentioned in this chapter see Gass and Harris [35] and the website Wikipedia, http://en.wikipedia.org/wiki/Main Page.Operations research has been used in the development of theories and methodologies and in applications in many areas of health services delivery. Some of these areas are strategic in decision making and others are operational. Some examples are:1. Health care and health care syst...