Defining Thai minority religions was as complex as defining Thai ethnic minorities. This problem was further compounded by the number of Thai whose Buddhism was a combination of differing beliefs. In the 1980s, the religious affiliation of the Chinese minority was particularly difficult to identify. Some adopted the Theravada beliefs of the Thai, and many participated in the activities of the local wat. Most Chinese, however, consciously retained the mixture of Confucian social ethics, formal veneration of ancestors, Mahayana Buddhist doctrine, and Taoist supernaturalism that was characteristic of the popular religious tradition in China. To the Chinese community as a whole, neither organized religion nor theological speculation had strong appeal. There were some Chinese members of the sangha, and most large Chinese temples had active lay associations attached to them. It was estimated in the 1980s that there were about twenty-one Chinese monasteries and thirteen major Vietnamese monasteries in Thailand.

The practice of Islam in the 1980s was concentrated in Thailand's southernmost provinces, where the vast majority of the country's Muslims, predominantly Malay in origin, were found. The remaining Muslims were Pakistani immigrants in the urban centers, ethnic Thai in the rural areas of the Center, and a few Chinese Muslims in the far north. Education and maintenance of their own cultural traditions were vital interests of these groups.

Except in the small circle of theologically trained believers, the Islamic faith in Thailand, like Buddhism, had become integrated with many beliefs and practices not integral to Islam. It would be difficult to draw a line between animistic practices indigenous to Malay culture that were used to drive off evil spirits and local Islamic ceremonies because each contained aspects of the other. In the mid-1980s, the country had more than 2,000 mosques in 38 Thai provinces, with the largest number (434) in Narathiwat Province. All but a very small number of the mosques were associated with the Sunni branch of Islam the remainder were of the Shia branch. Each mosque had an imam (prayer leader), a muezzin (who issued the call to prayer), and perhaps other functionaries. Although the majority of the country's Muslims were ethnically Malay, the Muslim community also included the Thai Muslims, who were either hereditary Muslims, Muslims by intermarriage, or recent converts Cham Muslims originally from Cambodia West Asians, including both Sunni and Shias South Asians, including Tamils, Punjabis and Bengalis Indonesians, especially Javanese and Minangkabau Thai-Malay or people of Malay ethnicity who have accepted many aspects of Thai language and culture, except Buddhism, and have intermarried with Thai and Chinese Muslims, who were mostly Haw living in the North.

The National Council for Muslims, consisting of at least five persons (all Muslims) and appointed by royal proclamation, advised the ministries of education and interior on Islamic matters. Its presiding officer, the state counselor for Muslim affairs, was appoibf3 ointed by the king and held the office of division chief in the Department of Religious Affairs in the Ministry of Education. Provincial councils for Muslim affairs existed in the provinces that had substantial Muslim minorities, and there were other links between the government and the Muslim community, including government financial assistance to Islamic education institutions, assistance with construction of some of the larger mosques, and the funding of pilgrimages by Thai Muslims to Mecca. Thailand also maintained several hundred Islamic schools at the primary and secondary levels.

During the sixteenth and seventeenth centuries, Portuguese and Spanish Dominicans and other missionaries introduced Christianity to Siam. Christian missions have had only modest success in winning converts among the Thai, and the Christian community, estimated at 260,000 in the 1980s, was proportionately the smallest in any Asian country. The missions played an important role, however, as agents for the transmission of Western ideas to the Thai. Missionaries opened hospitals, introduced Western medical knowledge, and sponsored some excellent private elementary and secondary schools. Many of the Thai urban elite who planned to have their children complete their studies in European or North American universities sent them first to the mission-sponsored schools.

A high percentage of the Christian community was Chinese, although there were several Lao and Vietnamese Roman Catholic communities, the latter in southeastern Thailand. About half the total Christian population lived in the Center. The remainder were located in almost equal numbers in the North and Northeast. More than half the total Christian community in Thailand was Roman Catholic. Some of the Protestant groups had banded together in the mid-1930s to form the Church of Christ in Thailand, and nearly half of the more than 300 Protestant congregations in the country were part of that association.

Other religions represented in Thailand included Hinduism and Sikhism, both associated with small ethnic groups of Indian origin. Most of the Hindus and Sikhs lived in Bangkok.

Data as of September 1987