In this interview excerpt, Niels Thygesen, Adviser to the Governor of the Danmarks Nationalbank from 1973 to 1983, Chairman of the Danish Economic Council from 1983 to 1985 and a member of the Delors Committee set up to study and propose practical steps that would lead to the gradual establishment of Economic and Monetary Union (EMU) from 1988 to 1989, describes the debate between a ‘common currency’ and a ‘single currency’ within the Delors Committee. He also mentions the discussions on the transitional phases between the main stages of a future economic and monetary union.