This chapter reconstructs the genesis and evolution of Gilbert Simondon'spsychologie génétique , arguing that psychology functions as a transversal axis through which the individuation ofphysical, biological, technical, and psychic realities can be understood in their mutual resonance. TracingSimondon's formative academic trajectory — from his early engagement with figures such as Merleau-Ponty,Piéron, Bachelard, Fraisse, and Canguilhem — the chapter charts the progressive consolidation of a geneticapproach to psychic life. Key moments include his encounter with cybernetics in the early 1950s and thearticulation, between 1956 and 1957, of a three-phase model of psychological theorisation moving from causaldualism through systematic monism to genetic pluralism. Drawing on unpublished lectures, manuscripts, andpublished texts, the analysis demonstrates that affectivity, imagination, and invention operate as primary vectors inthe genesis of subjectivity and collective becoming. Far from being peripheral to Simondon's broader philosophicalproject, genetic psychology is shown to anticipate and undergird the very possibility of a general theory ofindividuation. The chapter culminates in a close reading of Forme, information, potentiels, in which Simondon'sallagmatic approach integrates psychic individuation into a comprehensive transdisciplinary framework.