Sāsnā Phī (Lao: ສາສນາຜີ; Thai: ศาสนาผี Ṣāsnā phī, "religion of spirits") is a Thai and Lao term describing ethnic Tai folk beliefs.
Tai folk animist traditions are practiced by the Lao, Lao Isan and Thais of Thailand. These religions are pantheistic and polytheistic and their practice involves classes of shamans.
Animist beliefs are often practiced side by side in Thailand and Laos. Among the Lao, the Lao Loum and Lao Lom are predominantly Buddhist, while the Lao Theung and Lao Sung are predominantly folk religious. Tai folk animist traditions have also been incorporated into Laotian Buddhism.
Deities (ຜີ, ผี, [pʰiː]) in Sāsanā Phī comprehend tutelary gods of buildings or territories, of natural places, things or phenomena, as well as ancestral spirits and other spirits that protect people, and there are also malevolent spirits. Guardian deities of places, such as the phi wat (ຜີວັດ, ผีวัด) of temples and the lak mueang (ຫລັກເມືອງ, หลักเมือง, [lak mɯːaŋ]) of towns are celebrated with communal gatherings and offerings of food. Gods of Hindu derivation are included in the pantheon; indigenous non-Hindu gods are called phi thaen (ຜີແຖນ, ผีแถน). Gods are ubiquitous, and some of them are connected with the universal elements: heaven, earth, fire, and water.