Unlike many other Latin American nations (the other notable exceptions being Uruguay), the population of Argentina is heavily made up of inhabitants of European background - 97% , the largest being Italians and Spaniards. There are also significant German, Polish, French, British and Slavic populations.
After the regimented Spanish colonists, waves of European settlers came to Argentina from the late nineteenth to mid-twentieth centuries. Major contributors include Italy (initially from Piedmont, Veneto and Lombardy, later from Campania and Calabria),, Spain (foremost among them ethnic Galicians and Basques), and France (mostly to Buenos Aires and Mendoza). Smaller but significant numbers of immigrants came from Germany and Switzerland (in the so-called Lakes Region of Patagonia; and in Córdoba), Scandinavia (Denmark, Norway and Sweden), Greece, the United Kingdom and Ireland (to Buenos Aires, Santa Fé, and Patagonia; see also English settlement in Argentina), and Portugal. Eastern Europeans were also numerous, from Poland, Russia, Ukraine, Romania and Lithuania, as well as Balkan countries (Croatia and Montenegro, particularly in Chaco). There is a large Armenian community, and the Patagonian Chubut Valley has a significant Welsh-descended population. Smaller waves of settlers from Australia, South Africa and the United States are recorded in Argentine immigration records.
The majority of Argentina's Jewish community derives from immigrants of north and eastern European origin (Ashkenazi Jews), and about 15–20% from Sephardic groups from Spain. Argentina is home to the fifth largest Ashkenazi Jewish community in the world. According to the National Census, Jews make up about 2 percent of Argentina's population  (see also History of the Jews in Argentina).
In recent decades, especially during the 1990s, there has been an influx of immigrants from neighboring countries, principally Paraguay, Bolivia, and Peru.
Small but growing numbers of people from East Asia have also settled Argentina, mainly in Buenos Aires.
Argentina has a large Arabic community, made up mostly of immigrants from Syria and Lebanon.
The officially recognized indigenous population in the country, according to the "Complementary Survey of Indigenous Peoples" based on 2001 Census data, stands at approximately 402,921 people (about 1 percent of the total population)
Illegal immigration has been a relatively important population factor in recent Argentine demographics. Most illegal immigrants come from Bolivia and Paraguay, countries which border Argentina to the north. Smaller numbers arrive from Peru, Ecuador, Romania,Ukraine, and the People's Republic of China. The Argentine government estimates 750,000 are undocumented and has launched a program called Patria Grande
Uruguay is primarily populated by people of European origin. According to a study done in 1997, 94% of its population is of white European descent, Spaniards, followed closely by Italians, including numbers of British, Germans, French, Swiss, Russians, Portuguese, Poles, Bulgarians, Hungarians, Ukrainians, Lithuanians, Estonians, Latvians, Dutch, Belgians, Croatians, Greeks, Scandinavians, Irish, and Armenians.
Uruguay is the only country in the Americas where Amerindians are now absent. The remaining 6% of the inhabitants are of either African or Asian descent.
Chile is a relatively homogenous country and most of its population is of predominantly mestizo (60%) and of European origin (30%).
Mestizos in Chile have varying degrees of European and native American admixture, the product of the racial mixture between colonial Spanish immigrants and the native Amerindian tribes.
Relative to its overall population, Chile never experienced any large scale wave of immigrants like Argentina and Uruguay.
But non-Spanish European immigrants arrived in Chile - mainly to the northern and southern extremities of the country - during the 19th and 20th centuries, including English, Germans, Irish, Italians, French, Croatians (and other former Yugoslavians).
Native Americans make up 7% of the population. Asians like Japanese-Chileans, and Afro-Chileans, total percentage - under 1%.