In this interview excerpt, Guy de Muyser, Legation Secretary then Legation Counsellor in the International Economic Relations section of the Luxembourg Foreign Ministry from 1961 to 1969, describes the Foreign Ministry’s involvement in the negotiations that led to the signing of the Merger Treaty on 8 April 1965. He particularly focuses on the role played by Pierre Werner, Luxembourg Minister of State and Prime Minister from 1959 to 1974 and from 1979 to 1984 and Foreign Minister from 1964 to 1967.