The topic of legal pluralism has puzzled the sociology of law since its origins. To quote an early example, the aim of Eugen Ehrlich was to grasp the “colourful diversity of living law.” Max Weber, too, made a distinction between law beyond the state, on the one hand, and state law, on the other, the latter being the formal object of normative legal science. The concept of legal pluralism, later formulated in order to capture this diversity, gave rise, as is well known, to a specific line of inquiry in the domain of law and society; it has found concrete expression particularly in the Journal of Legal Pluralism, published under this title since 1981, and has triggered energetic debates. Jean-Guy Belley has made a crucial contribution to these debates, in particular by writing the entry on “pluralisme juridique” for the Dictionnaire encyclopédique de théorie et de sociologie du droit, published 1988. Years before, he had begun an ambitious research undertaking centred on legal pluralism as a fundamental paradigm for jurisprudence, first with a doctoral dissertation under the supervision of Jean Carbonnier and later as a professor in contract law and sociology of law at McGill University. This scholarly relationship to legal pluralism developed first in the domain of sociology of law, through a comprehensive approach that culminated in 1998 with the publication of Le contrat entre droit, économie et société.