Life is a quality that distinguishes physical beings having biological processes from those that do not. Plants, animals, bacteria, etc., are some of the various existing forms of life. Varied definitions of life have been put forward by scientists and philosophers over time. There also exist various schools of thought regarding the assessment of the quality of life. It is a subjective concept that varies with the population studied. It is generally conceptualized as a multi-dimensional construct made up of a number of independent domains encompassing physical health, psychological well-being, social relationships and functional roles. Different approaches, evaluations, methodologies and advanced studies on this topic have been included in this book. Such selected concepts that redefine quality assessment of life have been presented herein. A number of latest researches have been included to keep the readers up-to-date with the global concepts in this area of study.