The contemporary debate on the concept of health is basically between naturalists and normativists. The fundamental issue concerns the role of values with respect to the scope of medicine. In contrast, normativists argue that the concept of health is value-laden. A barrier to a generally accepted concept of health is this fundamental tension between normativists and naturalists. Philosophers, from antiquity until the present age, have written at length about the concept of health. A survey of a handful of introductory health texts reveals that physical health, mental health, social health, environmental health, spiritual health, and emotional health are some of the commonly discussed dimensions of health. Christopher Boorse is one of the most ardent and discerning defenders of a value-free naturalistic concept of health, which places an emphasis on the concept of function. The chapter also presents an overview on the key concepts discussed in this book.