The issue of cross-cultural similarities and differences in trance practitioners engaged in healing is examined, based on a formal quantitative cross-cultural study and analysis. The findings suggest distinct types of healers: shamans, shaman/healers, healers, and mediums. The data illustrate not only some universals of healers, but more importantly it reveals systematic differences between the shamans of hunting and gathering societies, the shaman/healers of agricultural societies, and the possessed mediums of politically stratified societies. These different types of trance healers are characterized and compared in order to illustrate the importance of terminological clarity, as well as to examine the characteristics and functions of shamanistic healers with respect to the social and cultural context of their activities.