Grasslands around the world provide most of the world's milk and wool and much of the meat. The growing world population and global warming have put increased pressure on the world's grasslands. Ross Humphreys has played a leading role in the development of grassland science and in this authoritative review discusses how it has evolved over the past sixty years. Using the proceedings of the International Grassland Congress since 1937, Humphreys identifies the shifting emphasis of the science, assesses the current situation and provides perspectives for its future direction.