Puerto Rico is aging more rapidly than almost any country, with 2020 estimates placing its population share of adults older than 65 as being the 10th highest in the world. Unlike most locales, Puerto Rico’s aging is driven by both (a) the culmination of long-running fertility and mortality trends and (b) high levels of outmigration of working-age adults, which contributes both directly (removal of young people) and indirectly (reduced births) to its pace of population aging. This article offers an overview of the main issues surrounding population aging in Puerto Rico. Policymakers and government leaders must plan for Puerto Rico’s unconventional population aging, which will exacerbate traditional concerns about the sustainability of government services and long-term economic prospects. Additional concerns emerge related to reduced social support networks and their impact on caregiving dynamics and implications for health. Puerto Rico’s unique history and political relationship with the United States present challenges and benefits for its aging population. Research on aging in Puerto Rico and public health policies must adapt to the needs of the country’s aging society.