Throughout the various stages of life, increasing levels of scientific and ethical attention are being directed to the consequences of medical intervention. The measures being studied are additional to the traditional indices of biological functioning and survival. Such monitoring is becoming especially important towards the end of life, where the cost of treatment ever rises in response to increasing technical sophistication. The downside to increasing longevity through such means is the burden of such treatments. What, then, is the balance between the duration of life gained and life quality? The readers of this Book mainly include health professionals e.g., physicians, nurses, psychologists etc. as well as students in the fields of medicine, nursing, psychology or social work. The contents can be also useful for health economists and health policy makers. It is essential to remember that quality of life is a very important tool for the evaluation of health policies.