This chapter deals with Boulez’s early knowledge of African, Asian and Latin American civilisations and musical cultures and the encounters and experiences which mediated it. The role of Messiaen’s harmony class, the training for an unrealised mission in Cambodia, the tours of South America with the Renaud-Barrault Theatre Company and the relationships with the ethnomusicologist André Schaeffner, from the post-war years to the beginning of the 1960s, are considered and contextualised with respect to the fields of contemporary French ethnology and ethnography. Boulez’s statements on ‘traditional cultures’ from his writings and correspondences are reconsidered against the background of colonial institutions and discourses and the transformations they were undergoing during the incipient phase of decolonisation. The composer’s analogical and comparatist habits, grounded in interwar models, are shown through the examples of his reflections on John Cage’s prepared piano (1949) and the staging of Schoenberg’s Pierrot Lunaire (1961).