In this chapter we explore how Catholic bioethicists can interpret the ethical foundations of Catholic social teaching to better apply them to questions arising in public health care. Decisions regarding public health interventions and policies are made by human agents. We propose that an adequate approach to public health ethics must attend not only to principles and concepts, but to a method by which agents reach concrete decisions in unique, complex, and evolving public health situations. The method elaborated in this chapter is G-O-A-LS, an acronym for the four components and the context of relationships that, we contend, are integrated in any ethical decision based on the general structure of human knowing, deciding, and loving. We show how principles of Catholic social teaching that can guide decision making in public health care are generalizations of good decisions reached by integrating the components of this method.