Meat and dairy products account for almost half of food-generated greenhouse gases (GHG), and as global consumption of livestock products continues to grow there is pressure on the livestock industry to lower its emissions. Poultry, pig, dairy, and feedlot production rely on the use of grains and oilseeds, increasing the demand for limited resources. With continued expansion of livestock production to meet global demand for protein, ruminant production will need to increase its use of forages. Unlike pigs and poultry, ruminants can utilize cellulosic materials to produce high quality protein for human consumption. Furthermore, perennial forages, forage-cropping rotations, and well-managed grazing lands provide numerous environmental benefits. However, high-fiber diets increase enteric CH₄ emissions from ruminants, so increasing forage use by ruminants may at first seem counterproductive in terms of reducing GHG emissions. However, there is increasing knowledge of mitigation practices that lower CH₄ emissions from cattle. Some strategies are (1) technologies to reduce methanogenesis in the rumen (nitrate, inhibitors), (2) improving fiber digestibility (pre-treatment, genetic selection of forages, harvest management), and (3) targeted supplementation and management of animals to improve productivity. When examining the total GHG emissions from a system, all emissions and removals of CH₄, N₂O, and CO₂ on the farm and from purchased inputs must be considered using a life cycle approach. Forage-based ruminant systems tend to be relatively low input with less fossil fuel CO₂ emissions and fertilizer-based N₂O emissions than grain-based systems. Use of N-fixing legume forages further displaces the use of fertilizers. With grazing systems, the nutrient cycle is relatively closed with excreted nutrients returned directly to the land. Well managed grasslands subject to moderate grazing can augment soil carbon reserves. Such lands also provide many other ecosystem services including conservation of biodiversity, water quality, and wildlife habitat. Thus, continued development and adoption of mitigation strategies will allow ruminant production systems to rely more extensively on forages while lowering GHG emissions and providing enhanced ecosystem services.