A walk-in is a new age concept of a person whose original soul has departed his or her body and has been replaced with a new soul, either temporarily or permanently.
Interest in the walk-in phenomenon was initially stimulated in the 1970s by the popular Seth Speaks series of occult books written by channel Jane Roberts, as reputedly authored by her various spirit-world benefactors. In 1979, Ruth Montgomery contributed to the fascination with Strangers Among Us, a collection of accounts of walk-ins. She included prominent historical figures among her subjects, such as Thomas Jefferson as having hosted walk-in spirits who actually wrote the Declaration of Independence.
Subsequently, a belief system grew up around the walk-in. It included New Age attributes such as the concept of ascending into higher frequencies of evolution, a variety of psi powers, traditional predictions regarding earth changes first cited in the Bible, and predictions of dire fates for those whose vibrational levels remain unraised. The New Age walk-in belief system now includes a number of variant experiences such as channeling, telepathy contact with extraterrestrial intelligences, or soul merging, where the original soul is said to remain present, coexisting or integrating with the new one.
The experiences are not regarded favorably by some religious groups and mental health professionals. Some psychiatrists believe that all of these experiences, from traditional walk-ins to the New Age variety up to and including cooperative healthy multiples, are an attention-seeking playacting, or at best a metaphor of distress to express something the client feels is wrong or somehow different from usual, but is having trouble describing.