Pierre Janet’s writings on schizophrenia, paranoia, and hallucinations occurred in the context of his general psychology of action, developed while he was Professor of Comparative and Experimental Psychology at the College de France and through his psychotherapy practice. Thus, in order to understand Janet’s ideas about hallucinations, paranoia, and schizophrenia, one must first understand some of the basic psychological tenets of his general psychology of action. He believed that all human behaviour could be conceptualized on a scale of tendencies. Janet also argued that humans ascribe a level of reality to internal or external events that could be conceptualized in terms of a hierarchy. In contrast, psychopathology involves insufficient force, inadequate tension, or a poor balance between the two, which often leads to the expression of actions inappropriate to a given situation. Janet’s therapeutic approaches involved directly assessing an individual’s psychological force and tension, and proposing unique solutions.