 In this entry, we provide an overview of the empirical literature regarding the social determinants of health, and the philosophical literature concerning the justice of health inequalities. Although the health care system is itself a determinant of health, we largely set aside questions regarding access to health care for it is covered elsewhere (see entry on  justice and access to health care).  We begin with a discussion of the social gradient in health, proposed social determinants of health, and possible causal pathways by which these socially controllable factors could affect people’s health. We also discuss the normative question of whether health inequalities should be understood and measured as differences among social groups or differences among individuals.