The global population is rising, but age structures differ significantly between developed and developing countries. China's youth population is sharply declining, creating challenges from past policies and demographic shifts. The USA and UK face slower declines, indicating aging population issues. Japan experiences the most severe decline, stressing urgent support for its aging society. India's large youth population presents a significant demographic dividend, impacting GDP growth. However, declining fertility rates and regional variations suggest the youth bulge may close soon. Eastern and northern states will maintain a youth bulge, while southern and western states have saturated. Differentiated regional policies are needed to leverage this demographic dividend. To harness demographic dividends, the chapter highlights critical needs such as increased investment in education and healthcare, the creation of productive job opportunities, relevant skills training, higher capital formation, and addressing gender gaps, among others.