The northwest of the country, the Nicoya peninsula, was the southernmost point of Nahuatl cultural influence when the Spanish conquerors (conquistadores) came in the 16th century.

[6] During most of the colonial period, Costa Rica was the southernmost province of the Captaincy General of Guatemala, which was nominally part of the Viceroyalty of New Spain (i.e., Mexico), but which in practice operated as a largely autonomous entity within the Spanish Empire.

Costa Rica's distance from the capital in Guatemala, its legal prohibition under Spanish law to trade with its southern neighbors in Panama, then part of the Viceroyalty of New Granada (i.e., Colombia), and the lack of resources such as gold and silver, made Costa Rica into a poor, isolated, and sparsely inhabited region within the Spanish Empire.

The small landowners' relative poverty, the lack of a large indigenous labor force, the population's ethnic and linguistic homogeneity, and Costa Rica's isolation from the Spanish colonial centers in Mexico and the Andes all contributed to the development of an autonomous and individualistic agrarian society.

The most-recent official 2022 census asked people to identify using multiple options including Indigenous, Black or Afro-descendant, Mulatto, Chinese, Mestizo, white and other on (Question 7) section IV.

European migrants used Costa Rica to cross the isthmus of Central America and to reach the USA's West Coast (California) in the late 19th century and until the 1910s (before the Panama Canal opened).

Many of the first Spanish colonists in Costa Rica may have been Jewish converts to Christianity who were expelled from Spain in 1492 and fled to colonial backwaters to avoid the Inquisition.

Today, according to modern DNA test data, the average Costa Rican (with 4 Costa Rican grand-parents) from the Central Valley is around 69–89% European, mainly Spanish, Basque, or Portuguese, with around 8–26% Native American DNA from Central America, Colombia, or Venezuelam, and 1–7% African particularly from Cameroon, Senegal or Congo.

Native Americans from other regions in the Americas, European Jewish, Italian, Irish, and Asian and Middle Eastern DNA can also be traced in part of the current Costa Rican population.

Moreover, Costa Rica took in many refugees from a range of other Latin American countries fleeing civil wars and dictatorships during the 1970s and 80s – notably from El Salvador, Chile, Cuba, and recently from Venezuela.

By 2019 the largest Immigrant Diasporas in Costa Rica are people from: Nicaragua, Colombia, Honduras, El Salvador, Venezuela, and the United States.

Because of the recent small but continuous immigration from Asia (including West Asia/the Middle East), other religions have grown, the most popular being Buddhism (because of a growing Han Chinese community of 40,000), and smaller numbers of followers of the Hindu, Jewish, Muslim and Baháʼí Faiths.

[17] The Church of Jesus Christ of Latter-day Saints (Mormons) claim more than 35,000 members and has a temple in San Jose that served as a regional worship center for Costa Rica, Panama, Nicaragua, and Honduras.

The main destination countries are the United States (85,924), Nicaragua (10,772), Panama (7,760), Canada (5,039), Spain (3,339), Mexico (2,464), Germany (1,891), Italy (1,508), Guatemala (1,162) and Venezuela (1,127).