In “The Fall of the House of Usher,” Edgar Allan Poe offers a pioneering study of folie à deux, today known as shared psychotic disorder, in which a person with a psychotic disorder induces a seemingly healthy person to experience a delusion and/or a hallucination. Drawing on psychological literature from the nineteenth to the twenty-first century, the article examines Roderick Usher as the inducer and the narrator as the induced. Roderick exhibits eccentric traits characteristic of schizotypal personality disorder and, as the tale unfolds, manifests symptoms of schizophrenia. While the narrator strives to hold onto his rationality, he eventually becomes, in his own words, “infected” by Roderick's superstitious beliefs. That infection leads to a hallucination of Roderick's twin sister, Madeline, as having escaped from a coffin within the family vault. The shock of seeing his friend's dramatic decline, the strain of trying to alleviate Roderick's grief, natural sympathy for his friend's plight, the power of Roderick's rhetoric, and strong suggestibility, heightened by an isolated and melancholy environment, lead the narrator to a shared psychosis. Never fully recovering from his nightmarish experience, the narrator feels compelled to relive the horror in relating his traumatic encounter with the Usher twins. Poe's evocative portrayal of the contagion of fear and its effect on perception reveals how psychologically prescient he was about shared psychotic disorder.