Few elements are as well studied by ecologists and biogeochemists as nitrogen as it cycles through living things and the Earth system. Due to the intentional and unintentional manufacture of reactive nitrogen (Nr) beginning with and continuing through industrial and agricultural revolutions, Nr is now abundant throughout the biosphere. It is a boon to human well-being and bane to the environment. Across the world there are entire regions that have been characterized as having either too much or too little N. The meanings behind this phrase differ depending on the region. In areas, such as North America where there is “too much N,” loss to the environment damages water quality, reduces biodiversity, creates ozone, regional haze, and promotes human respiratory diseases. However, these ailments are also prevalent in world regions with “too little N” with reduced food security where over-application of synthetic N fertilizers, uncontrolled sewage, and nitrogen oxide emissions create the worst of conditions for communities that are both food insecure and suffer pollution. A challenge for those attempting to craft meaningful Nr management policy is to promote policies and practices for best Nr management that can be adopted in both N-abundant and N-insufficient regions to increase equitable access to food and goods while protecting or restoring the clean air, clean water, and biodiversity benefits that are directly harmed from Nr leakage. The many pathways to impacts pass through the atmosphere, biosphere, and hydrosphere to cause a host of impacts influencing greenhouse gases, human health, terrestrial ecosystems, aquatic ecosystems, societal values, agricultural and non-agricultural products. These many pathways and impacts can be daunting to policy makers, and some countries, like the US, have adopted isolated cause-effect regulatory approaches one pathway at a time. But, like a game of whack-a-mole, Nr reduction in one sector may show up elsewhere. Far more sensible is to take an integrated approach toward Nr management and policy. To do that requires new ways of identifying pressure-impact relationships. Our session, linked to a large international program on nitrogen management, presents efforts being made to develop metrics and an epistemology for quantifying, communication, and managing, the impacts of N across sectors, societies, and international borders.