In this paper we present case studies of the efforts of five nations, Australia, Brazil, Ethiopia, Peru, and Zimbabwe, to use climate forecasts based on the El Niño-Southern Oscillation (ENSO) system to plan in advance of anticipated anomalous climatic states. We treat the variable use of climate forecasts among these nations as a problem of “fit” between the nature of ENSO, a persistent variability in the ocean–atmosphere system of the tropical Pacific which produces climate variability at local and regional scales around the world, and the human institutions and actors that make and use the forecasts. Our examination of patterns of use of forecasts indicates constraints and suggests opportunities for the useful application of climate forecasts in the future.