After the Second World War, in line with its new strategic choice Luxembourg resolutely set out on the road to international multilateralism and European integration, being in 1951 one of the six founding members of the European Coal and Steel Community (ECSC), and in 1952 - the workplace of the newly established European Community institutions. Since then, Luxembourg has played and continues to act as a mediator and a force for ideas in the EU, either as a member State, or through some of its leaders (including Joseph Bech, Pierre Werner, Gaston Thorn, Jacques Santer, Jean-Claude Juncker). Based on a wide range of sources from public and private archives, this presentation aims to illustrate how the Grand-Duchy had become a master of small states diplomacy and a consensus builder in the European integration history, and to demonstrate that the influential nature if its leadership gave Luxembourg a role that far outweighed the country’s socio-economic impact.