Pierre Janet's work represents one of the most rigorous foundations of modern clinical psychology. Despite its historical marginalisation, his theory of dissociation, methodological rigour, and conception of clinical practice continue to offer conceptual tools of great value for understanding trauma, psychopathology, and therapeutic processes. The Legacy of Pierre Janet: Theory, Method, and Clinical Practiceaims to bring Janet's thought back to the centre of contemporary psychological debate through a critical and selective re-examination of his most significant ideas. Drawing on an in-depth analysis of Janet's major works and his most emblematic clinical cases, the book argues that his approach represents a paradigmatic example of an idiographic orientation grounded in detailed clinical observation, abductive reasoning, and the integration of theory and practice. The book also addresses the complementarity between idiographic and nomothetic perspectives in Janet's thought, showing how single-case analysis can yield theoretically meaningful generalisations without reducing psychological phenomena to mere statistical abstractions. Structured into thematic chapters, each devoted to a central aspect of Janetian thought, the volume offers clinicians, researchers, and scholars a coherent framework for understanding the contemporary relevance of Janet's legacy and its potential contribution to current psychological theory and practice.