In spite of the fact that phli (spirit) worship has been officially banned, it remains the dominant non-Buddhist belief system in the country. Even in Vientiane. Luang Prabang citizens openly perform the ceremony called SII khwan or baasli (baci in the common French transliteration) in which the 32 guardian spirits known as khwan are bound to the guest of honor by white strings tied around the wrists. Each khwan is thought to be guardians over different organs - mental and physical - in a person's body.
Khwan occasionally wander away from their owner, which is really only a problem when that person is about to embark on a new project or on a journey away from home, or when they're very ill. Then it's best to perform the baasli to ensure that all the khwan are present and attached to the person's body.
Another obvious sign of the popular Luang Prabang devotion to phli can be witnessed in Vientiane at Wat Si Muang. The central image at the temple is not a Buddha figure but the lakmeuang in which the guardian spirit for the city is believed to reside. Many local residents make daily offerings before the pillar.
Outside the Mekong River valley, the phli cult is particularly strong among the tribal Thai, especially the Thai Dam, who pay special attention to a class of phli called ten. The ten are earth spirits that preside not only over the plants and soil, but over entire districts as well. The Thai Dam also believe in the 32 khwan, Maw (master/shaman), who are specially trained in the propitiation and exorcism of spirits, preside at important Thai Dam festivals and ceremonies.
The Khamu tribes have a similar hierarchy of spirits they can hrooi. The most important hrooi are those associated with guardianship of house and village. Ceremonies involving the hrooi have been closed to non-Khamu observers, so very little has been written about them.
The Hmong-Mien tribes also practice animism, 'plus ancestral worship. Some Hmong groups recognize a pre-eminent spirit that presides over all earth spirits; others do not. Some Hmong follow a type of 'cargo cult' in which they believe Jesus Christ will arrive in a jeep, dressed in combat fatigues. The Akha, Lisu and other Tibeto-Burman groups mix animism and ancestor cults; the Lahu add a supreme deity called Geusha.
A small number of Luang Prabang - mostly those of the remaining French-educated elite - are Christians. Various Christian missionary groups are trying to regain a foothold in Luang Prabang. Article 9 of the current Luang Prabang constitution, however, reads 'All acts of fomenting division among religions and among the people are prohibited', a clause interpreted to mean that religious proselytizing and the distribution of religious materials outside churches, temples or mosques, is illegal. Foreigners caught distributing religious materials may be arrested and held incommunicado or expelled from the country.
Several Christian groups have tried to evade the law by proselytizing in Luang Prabang under the guise of English-teaching or other aid work. This has made it somewhat more difficult for legitimate English teachers and small NGOs to obtain the proper permits to enter the country, as anyone from a group whose name isn't already known by the authorities to be legitimate may be suspected of being a Christian front.