The National Academies of Sciences, Engineering, and Medicine has produced a guide (based on papers that were presented at a public workshop in 2017) to demography of aging research trends and future directions. Harvard Bell Fellow Nikkil Sudharsanan, PhD, and faculty member David E. Bloom, PhD, have contributed a chapter that more closely examines the expected boom in population in low- and middle-income countries (LMICs), weighing the impact of both chronological and functional aging.