The French-Portuguese Ethnological Mission to Portuguese Timor (1966/1969) financed by French and Portuguese research bodies and initially directed by Louis Berthe was the first mission that conducted lengthy and thorough ethnographic research in East Timor vernaculars and with East Timorese communities. Using personal and scientific archives, printed and oral sources, this article analyses the mission's background, the role of Ruy Cinatti (a Portuguese poet, former colonial official in Timor and anthropologist trained in Oxford) in its launch, and its political and scientific context. The mission, undertaken during the Portuguese late colonial period and subject to the Portuguese authorities' approval and surveillance, marked East Timor as a site of anthropological inquiry into the Anthropology of European tradition produced in Southeast Asia, affiliated to post-war structuralism. This case study throws light on individual agency, Portugal's shortcomings in modern anthropology training, the international competition for Portuguese Timor as part of the Indonesian "field of ethnological study" and the transnational connections in its construction in the era of decolonization.