Mental mediumship is a complex process involving a variety of factors in need of further study before we can increase our understanding of the phenomenon. The purpose of this paper is to offer ideas and topics for further research--mainly from the psychological perspective and with emphasis on the old psychical research literature. The topics discussed are mediumistic trance (e.g., function, stages, and depth, mediumistic mentation (e.g., imagery, symbols), the dramatic capabilities of the subconscious mind, the relationship between mediumship and psychopathology, (...) the variety of experiences reported by mediums outside their performances (e.g., dissociative and ESP experiences), and the changing aspects of mediumship over time. It is argued that in-depth single case studies of specific mediums and interdisciplinary studies will greatly help us to understand mediumship more fully. Keywords: mediumship--mediumistic mentation--personation--iatrogenesis--trance--dissociation. (shrink)