El Nino has been with us for centuries, but now we can forecast it, and thus can prepare far in advance for the extreme climatic events it brings. The emerging ability to forecast climate may be of tremendous value to humanity if we learn how to use the information well. How does society cope with seasonal-to-interannual climatic variations? How have climate forecasts been used - and how useful have they been? What kinds of forecast information are needed? Who is likely to benefit from forecasting skill? What are the benefits of better forecasting? This book reviews what we know about these and other questions and identifies research directions toward more useful seasonal-to-interannual climate forecasts. In approaching their recommendations, the panel explores: vulnerability of human activities to climate; state of the science of climate forecasting; how societies coevolved with their climates and cope with variations in climate; how climate information should be disseminated to achieve the best response; and how we can use forecasting to better manage the human consequences of climate change.