The employment in 1954 of the Portuguese architect Luís Possolo (1924-1999) into the Lisbon-sited Gabinete de Urbanização do Ultramar (Overseas Urbanization Office – GUU) – which the Overseas Minister Marcelo Caetano had started ten years before – coincided with his sending to attend the inaugural edition of the course in Tropical Architecture at London’s Architectural Association. Scientific matter in this article is raised, on one hand, from a revision of state-of-the-art literature on the subject, and on the other hand on primary sources from that State Office, to be found at Lisbon’s Arquivo Histórico Ultramarino, along with data in the architects’ personal papers. The exercise adds relevant information for a broader understanding of that course at the AA, which would have a wide international repercussion in the field of researching and designing in architecture for the tropical regions through the following decades. The influence Possolo had on project designing at the GUU, and particularly his work as an architect for the Portuguese Overseas, shall also be engaged, as his major projects made in the civil service, as well as in private practice, are presented.