This article traces the attempts of Victorian spiritualist critics and novelists to reform the ghost story along naturalist lines, a move that demonstrates the hitherto neglected affinity between spiritualism’s and naturalism’s modes of theorizing human agency. The praise for the new French realism in British spiritualist journals such as Light, I argue, represents the movement’s enduring kinship with the theories of biodeterminism and of authorship as impersonal experimentation espoused by Émile Zola in Le Roman Expérimental. This affinity allows us to recognize fin-desiècle spiritualist fiction, not as a subgenre of the Gothic, but as a radical form of experimental realism.