Abstract
The recent attention to health systems has reignited the debate on some of the dichotomies that have persisted for decades in the global health field: prevention versus treatment, primary versus specialized care, vertical versus horizontal strategies, and social determinants of health versus health services. This chapter provides a conceptual basis to advance the understanding of health systems. It helps settle the disputes between vertical and horizontal approaches in order to improve health through the construction of a “diagonal” perspective. The chapter talks about health systems, and revisits the debate around vertical and horizontal approaches to healthcare. It discusses the main features of the diagonal approach and exemplifies the use of this approach by addressing the issue of child mortality in Mexico. The chapter concludes with a brief reflection of the strengths and potential limits of the diagonal perspective.