Do the dynamics of human population-rates of growth, age structure, distribution and more-influence when and where warfare will next break out? The findings of this report suggest that the risks of civil conflict (deadly violence between governments and non-state insurgents, or between state factions within territorial boundaries) that are generated by demographic factors may be much more significant than generally recognized, and worthy of more serious consideration by national security policy makers and researchers. Its conclusions-drawn from a review of literature and analyses of data from 180 countries, about half of which experienced civil conflict at some time from 1970 through 2000-argue that: Recent progress along the demographic transition-a population's shift from high to low rates of birth and death is associated with continuous declines in the vulnerability of nation-states to civil conflict. If this association continues through the 21st century, then a range of policies promoting small, healthy and better educated families and long lives among populations in developing countries seems likely to encourage greater political stability in weak states and to enhance global security in the future.