Population health as developed by the Canadian Institute for Advanced Research (CIAR) has influenced the shape and direction of Canadian public health policy, and has the potential to do so in the USA and elsewhere. There is reason to be concerned about this ascendence of CIAR thinking: population health is rooted within epidemiology, a militantly quantitative discipline; population health eschews analysis of societal structures as determinants of health; and population health elevates scientific understanding over health promotion action. Its lack of an explicit values base is also problematic. Policy makers should recognize these and other limitations as they consider models for a new public health.