The philosophy of critical realism associated with Roy Bhaskar has been winning influence in sociological circles since his early writings in the 1970s. It remains a dynamic and evolving philosophy, taken up and developed by influential sociological theorists like Margaret Archer. It has also had a considerable impact on the sociology of health and healthcare. In this chapter we start by introducing Bhaskar’s “basic” and “dialectical” critical realism and briefly comment on Margaret Archer’s critical realist-informed sociology before showing why his considerable body of work is of relevance to the sociological project and to sociological practice. The bulk of the chapter is then committed to illustrating just how critical realism can serve as a useful “underlaboring philosophy” for sociologists in the health field by focusing in some detail on theories and research on health inequalities in the United Kingdom (UK).