Chapter Two surveys what we call ‘physical-psychical scientists’ - physical scientists who, from the early nineteenth to the early twentieth century, showed some kind of interest in psychical phenomena. It uses the membership of Society for Psychical Research to identify many such physical-psychical scientists.Analysing this membership, and individuals who expressed their psychical interests outside the organisation, the chapter argues that these interests were far more extensive and complex than historians have argued.The chapter analyses the ways in which this collective interest was facilitated by existing institutional and other connections.It explores the range of intellectual, religious, moral and emotional reasons that underpinned this interest, the different positions and conclusions that different scientists reached after their investigations, and the reaons why so many scientists abandoned their interest in such studies or were actively hostile to them.