In the 1920s and ’30s, people gathered in darkened rooms to explore the paranormal through seances. Science of the Seance resurrects the story of a select transnational group and their quest for objective knowledge of the supernatural world, casting new light on empiricism and its relationship to gender, sexuality, and the body in this era. Drawing on publications, correspondence, seance notes, and photographs from Canada, the UK, and the US, Beth A. Robertson draws back the curtain to reveal a world inhabited by researchers, spirits, and spiritual mediums, including the notorious Mina “Margery” Crandon. Representing themselves as masters of the senses, untainted by the effeminized subjectivity of the body, psychical researchers believed that machines and empirical methods could transform the seance from an isolated spiritual encounter into a transnational empirical project. The laboratory of the spirits that they created, however, opened up a space where mediums and ghostly subjects could and did challenge their claims to exclusive scientific expertise and authority. This innovative reassessment of paranormal investigation and the transatlantic ties of the seance reveals how science, metaphysics, and the senses collided to inform gendered norms in the interwar era.