As elsewhere in the Spanish Empire, the original Spanish colony of Hispaniola employed a social system known as casta, wherein Spaniards born in Spain occupied the highest echelon. These were followed, in descending order of status, by: criollos, castizos, mestizos, mulattoes, Indians, zambos, and lastly, black slaves. The stigma of these social strata persisted for many years, reaching its culmination in the Trujillo regime, as the dictator used racial persecution and nationalistic fervor against Haitians.

According to a study by the CUNY Dominican Studies Institute, about 70% of the contemporary Dominican population has African ancestry. Most Dominicans self-identify as being of mixed-race rather than black. A variety of terms are used to represent a range of skintones depending on ancestry, such as morena (brown), canela (red/brown) ["cinnamon"], india (Indian), blanca oscura (dark white), and trigueño (wheat colored), among others.

Many have claimed that this represents a reluctance to self-identify with African descent and the culture of the freed slaves. According to Dr. Miguel Anibal Perdomo, professor of Dominican Identity and Literature at Hunter College in New York City, "There was a sense of 'deculturación' among the African slaves of Hispaniola. [There was] an attempt to erase any vestiges of African culture from the Dominican Republic.

The Haitian occupation government (1822-1844) invited free blacks and fugitives from the United States to settle on the island. In the late 1800s and early 1900s large groups immigrated to the country from Venezuela and Puerto Rico, so much so that two of the country's former presidents and life long political rivals, Juan Bosch and Joaquín Balaguer, had Puerto Rican parents.

During the first decades of the 20th century, many Chinese, Arabs (primarily from Lebanon and Syria), Japanese and to a lesser degree Koreans settled in the country, working as agricultural laborers and merchants. Waves of Chinese immigrants, the latter ones fleeing the Chinese communist People's Liberation Army (PLA), arrived and worked in mines and building railroads. The current Chinese Dominican population totals 15,000. The Arab community is also rising at an increasing rate. Estimates are at 3,400. Japanese immigrants, who mostly work in the business districts and markets, are at an estimate of 1,900 living in the country. The Korean presence is minor but evident at a population of 500.

In addition, there are descendants of immigrants who came from other Caribbean islands, including St. Kitts and Nevis, Dominica, Antigua, St. Vincent, Montserrat, Tortola, St. Croix, St. Thomas, Martinique and Guadeloupe. They worked on sugarcane plantations and docks and settled in the cities of San Pedro de Macoris and Puerto Plata. They are believed to number 28,000. Immigration from Europe and the United States is at an all time high, according to the Joshua Project and BBC: 1,400 Britons reside on the island, in addition to 800 Germans, 4,000 Italians (unofficially, the number is estimated to be as high as 40,000), 1,900 French, 88,000 Spaniards and (in 1999) 82,000 Americans. The town of Sosúa has many Jews who immigrated before or during World War II. The country is now home to 100 Jews.

With recent decades of unrest and poverty in Haiti, immigration from Haiti has increased once again. Some Haitian immigrants arrive in the Dominican Republic illegally and work at low-paying, unskilled labor jobs, including construction work, household cleaning, and in sugar plantations. Current estimates put the Haitian–born population in the Dominican Republic as high as 1 million. Working conditions on these sugar plantations have caused controversy, including allegations that they border on slavery. Moreover, the children of illegal Haitian immigrants are denied citizenship and basic health care, and there are frequent physical attacks on, and roundups of adult immigrants.

Haiti, with more people but half the land area, is much poorer than the Dominican Republic. Dictatorships failed to provide for education and training, political unrest kept the country in turmoil, and population pressure through subsistence farming has stripped the landscape. In 2002 less than half of the Haitian population had formal jobs; in 2003 60% of the Haitian population was illiterate, and 80% of all Haitians were poor. Facing stark prospects for survival, many Haitians cross the border to Dominican soil without authorization in search of better living conditions. But, as is usual for illegal immigrants in nearly all nations, they are relegated to working class status, largely in farming, often sugar cane plantations, and house construction, with poor housing and poor schools for their children.

Any person born on Dominican soil is a Dominican citizen if one of his or her parents is a legal resident of the country, per the Dominican constitution, unless the parents constitutions states otherwise( jus sanguinis) and any legally residing person in the Dominican Republic can theoretically become a citizen. Many children of Haitian ancestors are stateless, as their parents are denied Dominican citizenship because they are deemed to be transient, or illegal or undocumented residents, or are unable to obtain Haitian citizenship for lack of proper documents or witnesses: note that Haiti's Constitution states in Title II, Article 11 that "Any person born of a Haitian father or Haitian mother who are themselves native-born Haitians and have never renounced their nationality possesses Haitian nationality at the time of birth."

A large number of Haitian women, often arriving with several health problems, cross the border to Dominican soil during their last weeks of pregnancy to obtain much-needed medical attention for childbirth, since Dominican public hospitals do not refuse medical services based on nationality or legal status. Statistics from a hospital in Santo Domingo report that over 22% of childbirths are by Haitian mothers (a very underestimated number.) nu. Unofficially there are 800,000 illegal Haitians living in the Dominican Republic, which accounts for about 10% of the national population.] Other estimates give a figure of more than a million.

This information was obtained through the Internet via Wikipedia.