A history of food systems in Africa's Great Lakes region is presented using mostly historical linguistic sources, with help from archaeology and paleoecology. The paper moves beyond understanding the causes and consequences of iron-working as the most important feature of the period between c. 1000 B.C. and c. A.D. 500. I argue that a history of agriculture both gives context to changes in technology and introduces powerful new explanations for historical processes of settlement and occupational specialization that took place. Between 1000 B.C. and 500 B.C., in the Great Lakes region, speakers of three of Africa's four major language families practiced distinguishable food-producing systems. Two groups, Central Sudanian and Sog Eastern Sudanian, depended mainly on growing cereals and raising livestock for their sustenance. The third group, the Tale Southern Cushites, gave decidedly greater emphasis to cattle but probably also grew grains. A fourth group, the Great Lakes Bantu, grew root crops, fished and raised cattle and grain. They inherited much of their knowledge of these techniques, other than cattle-raising, from earlier Eastern Highlands Bantu-speakers. But they incorporated cattle and some grains through long-standing contacts with the two Sudanian and the Southern Cushitic communities. The eclectic food system they thus created allowed them to carry their unified, complex food-producing system throughout the wide variety of environments that they encountered in the Lakes region. After c. A.D. 200 descendants of the Great Lakes Bantu refined this synthesis; they emphasized livestock raising inland from Lake Victoria, and mixed farmers spread throughout the Kivu Rift. Technological, demographic, ecological and sociological explanations of the technological evidence are offered.