<p> Savanna ecosystems play a major role in the natural landscape and in the economic life of vast areas of the tropics. These grasslands are inherently fragile, yet Third World economic development makes human exploitation inevitable. The question that remains is whether utilization of the savannas for agriculture and other purposes will create sustained economic growth or a desert waste. <p> Guillermo Sarmiento is an unquestionable authority on the grasslands of the New World. His book is the first modern, integrated view of the genesis and function of this important natural system--a synthesis of savanna architecture, seasonal rhythms, productive processes, and water and nutrient economy. Sarmiento's emphasis is on the Venezuelan savannas that he has spent a lifetime studying, but his outlook is far broader. He makes frequent comparisons with other neotropical and tropical savannas and with temperate prairies, and he offers conclusions of global importance, not only for ecologists and agronomist but for anyone concerned with the politics of Third World development.