Reductions (Spanish: reducciones, also called congregaciones; Portuguese: redução, pl. reduções) were settlements created by Spanish rulers and Roman Catholic missionaries in Spanish America and the Spanish East Indies (the Philippines). In Portuguese-speaking Latin America, such reductions were also called aldeias. The Spanish and Portuguese relocated, forcibly in many cases, indigenous inhabitants (Indians or Indios) of their colonies into urban settlements modeled on those in Spain and Portugal.

The word "reduction" can be understood wrongly as meaning "to reduce." Rather, the Royal Academy of Spain defines reducción (reduction) as "a grouping into settllement of indigenous people for the purpose of evangelization and assimmilation." In colonial Mexico, they were called "congregations" (congregaciones). The goal of forced resettlements were to concentrate indigenous people into communities, facilitating civil and religious control over populations. The concentration of the indigenous into towns facilitated the organization and exploitation of their labor. The practice began during Spanish colonization in the Caribbean, relocating populations to be closer to Spanish settlements, often at a distance from the their home territories and likely facilitated the spread of disease. Reductions could be either religious, established and administered by an order of the Roman Catholic church especially the Jesuits, or secular, under the control of Spanish or Portuguese governmental authorities. The best known, and most successful, of the religious reductions were those created by the Jesuits in Paraguay and neighboring areas in the 17th century. The largest and most enduring secular reductions were those imposed on the highland people of the former Inca Empire of Peru during the rule of Viceroy Francisco de Toledo (1569–1581).