Diesel engines used in non-road vehicles and equipment are a significant source of pollutant emissions that contribute to poor air quality, negative human health impacts, and climate change. Efforts to mitigate the emissions impact of these sources, such as regulatory control programs, have played a key role in air quality management strategies around the world, and have helped to spur the development of advanced engine and emission control technologies. As non-road engine emissions control programs are developed in a growing number of countries around the world, it is instructive to look at the development of programs in two of the regions that have progressed furthest in controlling emissions from non-road engines, the United States (U.S.) and European Union (EU). This study reviews the development of non-road diesel engine emission control strategies and technologies in response to increasingly stringent emission control programs in the U.S. and EU, focusing specifically on engines used in the agriculture and construction sectors. Key technology transitions are tracked beginning with the introduction of regulatory programs in the mid-1990’s and continuing through proposed European Stage V regulations. These technology pathways are used along with a novel non-road emission inventory model to assess the potential for reductions in air pollutant emissions from the Indian non-road sector through the adoption of world-class emission standards.