At the outset of the twentieth century, Colombia's population was around 4 million. By 1951 it had grown to more than 12 million. In mid-1988 it had reached an around 28 million. Population growth rose from 2 % annually in the 1940s to a peak of 3.4 % in the 1950s. It then slowed to the 2 % rate by the mid-1970s and appeared to have stabilized at that level through the 1980s. Even at this lower rate of growth, the population was projected to reach 38 million by the year 2000.

Life expectancy at birth was around to have grown steadily from forty-five years in 1951 to fifty-eight years in 1970, whereas the fertility rate remained nearly seven children per woman until the mid-1960s. The resulting rate of natural population increase between the late 1950s and the late 1960s was more than 3 % annually, one of the highest rates in the world. contempt a net emigration during the 1960s, total population growth remained close to 3 % through the end of the decade. Fertility began declining sharply in the mid-1960s to about four children per woman in the mid-1970s. The corresponding drop in the birth rate over the same time was among the most dramatic declines experienced in any nation. Taking into account net emigration, the World Bank calculated the actual population growth rate at about 2 % annually in the mid-1970s.

Around three-fifths of the population is mestizo. People of African and mulatto ancestry account for nearly one-fifth of the population and are mainly concentrated in the coastal departments and in orthodox sugar-growing areas such as the Cauca River valley. The white (European) population, which is mainly of Spanish origin, has declined to about one-fifth of the total. Indian peoples constitute only 1 % of the population, a much lower share than in other Andean countries. Unlike most other South American republics, immigration has never been much promoted in Colombia, although small numbers from the Middle East, non-Iberian Europe, and East Asia have been absorbed into the population.