 We then address the central question of this entry: what makes a health inequality unjust, when it is unjust? We first focus on the justice of domestic health inequalities, providing an overview of prominent theoretical approaches to this question. Since many propose that health inequalities are not unjust when due to the voluntary choices of individuals, we next explore the issue of individual responsibility for health and its implications for health policy. We conclude with a discussion of the justice of global health inequalities.