The committee worked on two main topics, one was the creation of a general common market and the other one was the establishment of a European Community for the peaceful use of atomic energy.
The steering committee was composed of Paul-Henri Spaak, the six heads of delegation from the ECSC member states and a representative, Russell Frederick Bretherton, of the United Kingdom.
In addition several highly specialised subcommittees would then be set up, depending on the topics raised, which might relate to either customs or nuclear matters.
In October 1955 the United Kingdom decided to leave the Spaak Committee as the UK opposed a customs union and did not want to submit its atomic research program to Euratom.
The Spaak report was presented to the foreign ministers of the six Member States of the ECSC on 21 April 1956 and at the Venice conference one month later.