This chapter, which grew out of a Greenwall Foundation–funded working group of a dozen or so ethicists, lawyers, and public health practitioners, provides a rough conceptual map of the terrain of public health ethics. It examines the nature of public health and public health interventions, and it identifies a number of general moral considerations (principles) relevant to public health policy and practice and often, especially as articulated in basic human rights, promotive of public health. Because these moral considerations are general and broad, they require specification and weighting. In cases of conflict, five “justificatory conditions” need to be met: effectiveness, proportionality, necessity, least infringement, and public justification. These conditions help to determine whether protecting or promoting public health warrants overriding individual liberty in particular situations.