The second half of the twentieth century witnessed a significant transformation in the research culture of the Geneva School, marking a shift from the tradition of the Rousseau Institute to the Piagetian phase. The establishment of the International Centre for Genetic Epistemology (CIEG) in 1955, under the direction of Jean Piaget, served as an institutional catalyst for this change. It introduced a new mode of knowledge production grounded in interdisciplinary collaboration and an unprecedented organization of scientific work. The CIEG became an international intellectual laboratory, bringing together specialists from multiple disciplines around the program of genetic epistemology. This initiative integrated empirical research on child development with epistemological reflections of a general scope. This configuration reshaped the dynamics of research: rather than isolated individual or disciplinary efforts, an international community of researchers was consolidated, working collaboratively on shared problems. They exchanged methods, data, and engaged in debate within a framework that combined methodological rigor with an atmosphere of informality and intellectual autonomy, two distinctive traits of this institutional framework. The annual rhythm of collective work fostered the free exchange of ideas and the co-construction of knowledge, culminating in numerous publications and the consolidation of a shared interdisciplinary language. The CIEG provided resources, networks, and an innovative environment that altered the way research was conducted in Geneva, while simultaneously positioning developmental psychology at the core of a non-speculative epistemology. In sum, the launch of the CIEG redefined the Geneva School by replacing traditional pedagogical-psychological approaches with a new research paradigm characterized by disciplinary convergence, collective knowledge production, and a renewed international impetus to the Piagetian project.