Many other commentators have noticed an upsurge in spirit possession practices in East and Southeast Asia, resulting in a growing scholarship on spirits, ghosts, possession and shamanism over the last two decades.1 Some scholars distinguish between shamanism - where the shaman’s soul leaves the body to engage with the spirit world (Vitebski 2001) - and spirit possession or spirit mediumship - where the medium’s body acts as a vessel for spirits to enter and engage with this world. In Vietnam spirit mediumship is the most common form, and lately there has been a veritable explosion in mediumship practices and in scholarship about it. This chapter surveys some of that scholarship and pays particular attention to the - simultaneously theological and political - question whether spirit possession constitutes a religion. (Obviously, the fact that this chapter appears in a Handbook on Asian Religions partly gives away my answer.) The mushrooming of spirit worship and spirit possession is part of a wider process of reenchantment and re-ritualization in Vietnam, as evidenced by: the ubiquity of festivals and pilgrimages; the proliferation and beautification of religious shrines and temples; the ritualization of daily and political practices; and more visibility of religious behavior in public life (DiGregorio and Salemink 2007; Taylor 2007). Most of the scholarly focus - both Vietnamese and foreign - has been on mother goddess worship in the North, known as lên d-ôʼng (riding the medium), but spirit possession traditions in other parts of Vietnam such as hâ‘u bóng (serving/incarnating the spirit), hâ‘u vui (cheerful incarnation) and nhâ. p hôʼn (incarnation by souls) largely remains under the radar in other parts of Vietnam as well as in other religious traditions.