Despite renewed interest in population health concerns, elevation of this field in policy considerations faces many challenges. At present there is much concern about disparities and meeting improved population health objectives,but interest waxes and wanes with scientific developments and especially with dominant political alignments and ideologies. If the field of population health is to have sustained policy influence, it requires a persistent constituency, a strong organizational base both within and outside of government, and academic respectability. Population health faces many issues in seeking to become legitimized as both a unique field of study and as a significant force in public policy. Among these are a clear definition of the boundaries of the field, a continuing flow of resources for development, and attractive career structures for new recruits and future leaders.