This chapter focuses on Esping-Andersen's theory of "the three worlds of welfare capitalism' and its contribution to the understanding of population health and health inequalities. Although several recent empirical studies have examined how population health and health inequalities vary within welfare states, it seems important to thoroughly discuss these issues from a theoretical point of view This chapter starts with a discussion of some central aspects of Esping- Andersen's theory. Recent modifications/additions to Esping-Andersen's welfare regime theory will also be touched upon, together with some critiques of his ideas. Furthermore, some of the potential pathways through which welfare states can influence health and health inequality are discussed, and some empirical studies that have examined such relationships are presented. Finally, some concluding remarks on the usefulness of including Esping-Andersen's theory within health research are provided.