As a bridge between the largely conceptual discussion of Chapter 2 and the forecasting analyses to come, this chapter turns to the more technical topic of how we can best forecast global health futures. We can differentiate tools for looking at the future of global health on several dimensions of coverage and aggregation: whether they are country-specific or multicountry; whether they focus on morbidity, mortality, or both; whether they treat health in the aggregate or consider specific causes of morbidity and mortality; whether they forecast for 10 years or 25 years or even more.