Most houses are made of materials obtained from coconut and pandanus trees. Frequent droughts and infertile soil hinder reliable large-scale agriculture, so the islanders have largely turned to the sea for livelihood and subsistence. Most are outrigger sailors and fishermen. Copra plantations serve as a second source of employment.

 In recent years large numbers of citizens have moved to the more urban island capital of Tarawa. Increasing urbanisation has raised the population of South Tarawa to 50,182.

The native people of Kiribati are called I-Kiribati. Ethnically, the I-Kiribati are Micronesians. Recent archaeological evidence indicates that Austronesians originally settled the islands thousands of years ago. Around the 14th century, Fijians, Samoans, and Tongans invaded the islands, thus diversifying the ethnic range and introducing Polynesian linguistic traits. Intermarriage among all ancestral groups, however, has led to a population reasonably homogeneous in appearance and traditions.

The people of Kiribati speak an Oceanic language called "Gilbertese". Although English is also an official language, it is not used very often outside the island capital of Tarawa. It is more likely that English is mixed in its use with Gilbertese. Older generations of I-Kiribati tend to use more complicated versions of the language.

Christianity is the major religion, having been introduced by missionaries in the 19th century. The population is predominantly Roman Catholic (56%), although a substantial portion of the population is Congregationalist Protestant (34%).

 Many other Protestant denominations, including more evangelical types, are also represented. The Bahá'í Faith religion also exists in Kiribati (2.2%), along with Jehovah's Witnesses and The Church of Jesus Christ of Latter-day Saints (LDS Church) (4.7%). The Church of Jesus Christ of Latter-day Saints self-reports a membership of 15,364 (14.6%) at the end of 2011.

The population of Kiribati has a life expectancy at birth of 60 years (57 for males, and 63 for females) and an infant mortality rate of 54 deaths per 1,000 live births.Tuberculosis is present in the country.

Government expenditure on health was at US$268 per capita (PPP) in 2006. In 1990–2007, there were 23 physicians per 100,000 persons.Since the arrival of Cuban doctors, the infant mortality rate has decreased significantly.

Most health problems are related to consumption of semi-raw seafood, limited amount of food storage facilities, and bacterial contamination of fresh water supplies. In the early 2000s, between 1 and 7% of the population, depending on the island, were annually treated for food poisoning in a hospital.

 Modernization and cross-cultural exchange of the late 1900s brought new issues of unhealthy diet and lifestyle; heavy smoking, especially among the young population; and external infections, including HIV/AIDS.

Kiribati is the country with the third highest prevalence of smoking, with 54% of the population reported as smokers.