Felicitas D. Goodman was an American linguist and anthropologist. She was a highly regarded expert in linguistics and anthropology and researched and explored Ecstatic Trance Postures for many years. She studied the phenomenon of "speaking in tongues" in Pentecostal congregations in Mexico. She is the author of such well-received books as Speaking in Tongues and Where the Spirits Ride the Wind: Trance Journeys and Other Ecstatic Experiences. Her work has been published mostly in the United States and Germany.

Speaking in tongues, also known as glossolalia, is an activity or practice in which people utter words or speech-like sounds, often thought by believers to be languages unknown to the speaker. One definition used by linguists is the fluid vocalizing of speech-like syllables that lack any readily comprehended meaning. In some cases, as part of religious practice, some believe it to be a divine language unknown to the speaker. Glossolalia is practiced in Pentecostal and charismatic Christianity, as well as in other religions.