More accurate forecasts of climate conditions over time periods of weeks to a few years could help people plan agricultural activities, mitigate drought, and manage energy resources; however, current forecast systems have limited ability on these time scales. Models for such climate forecasts must take into account complex interactions that can be difficult to represent realistically. To improve the quality of forecasts, this book makes recommendations about the development of the tools used in forecasting, specific research goals for improving understanding of sources of predictability, and best practices to improve how forecasts are made and disseminated.