We provide a unifying framework for the evaluation of population health. We formalize several axioms for social preferences over distributions of health. We show that a specific combination of those axioms characterizes a large class of population health evaluation functions combining concerns for quality of life, quantity of life and health shortfalls. We refer to the class as (unweighted) aggregations of health-adjusted life years (HALYs). Two focal (and somewhat polar) members of this family are the (unweighted) aggregations of quality-adjusted life years (QALYs), and of disability-adjusted life years (DALYs). We also provide new characterization results for these focal members that enable us to scrutinize their normative foundations and shed new light on their similarities and differences.