The aim of this chapter is to present the Danish Nitrogen Mitigation Assessment (www.DNMARK.org), an ongoing five-year multidisciplinary research alliance, focusing on the quantification of nitrogen (N) flows and solutions scenarios for a more sustainable N use in Denmark. As one of the world’s most agriculturally intensive countries, with a long N regulation history, and state-of-the-art monitoring of developments in key indicators for nitrogen losses, use and efficiency, Denmark is a case of special interest. Based on the results and recommendations from the European Nitrogen Assessment, DNMARK addresses all parts of the N cascade, and demonstrates results both at the landscape scale and the national scale. The national N flows and N balance are accounted for 1990–2010, and methods for the downscaling of these results to regional pilot study areas are developed, together with approaches for the integrated assessment and modelling of the three main types of solution scenarios defined: (i) New production chains with a more efficient use and recycling of N, (ii) Geographically differentiated N-measures implemented by cost-effective instruments with localized planning and management of agricultural landscapes, and (iii) Changed consumption patterns driving land use change and reducing N use.