In the temperate regions of the world ryegrasses comprise the main sown forage grasses of which the outbreeding perennial, Italian and Westerwolths ryegrasses are the most economically important. This chapter presents information on the origin and systematics of these forage grasses which share a high degree of genome ancestry with the cereals originating in the eastern Mediterranean basin. It considers how plant breeding has enhanced natural genetic resources to produce valuable new varieties with improved production and livestock nutrition characteristics together with increased tolerance of environmental stresses caused by biotic (pests and diseases) and abiotic (temperature, water and mineral extremes) pressures. The challenge of maintaining the optimum balance between vegetative growth and seed production is also addressed. Breeding methodologies based on traditional techniques are discussed and the integration of new biotechnologies into breeding programmes is reviewed. Breeding achievements are evaluated and future goals considered in relation to the increasingly diverse demands placed on grassland to provide ecosystem services, amenity value and systematic breeding as well as providing feed for ruminants.