On 26 August 1955, with a view to the Noordwijk Conference, Auguste Vanistendael, Secretary-General of the International Confederation of Christian Trade Unions (ICCTU), forwards to Paul-Henri Spaak, President of the Intergovernmental Conference established by the Messina Conference, a letter in which he outlines his hope that the trade unions will be invited to take part in the work of the Spaak Committee.

Im Februar 1956 spricht sich die Wirtschaftsvereinigung der deutschen Eisen- und Stahlindustrie gegen eine Fortsetzung der Integration in Europa nach Wirtschaftssektoren aus, anstatt der allgemeinen Integration, für die sich die Sechs nach der Konferenz von Messina entschieden hatten.

Am 4. Februar 1956 richtet Fritz Berg, Präsident des Bundesverbandes der Deutschen Industrie, ein Schreiben an Bundeskanzler Konrad Adenauer, in dem er seine Besorgnis angesichts der Fortsetzung der europäischen Integration im Bereich der Kernenergie zum Ausdruck bringt, die zu Lasten der anderen von den Sechs auf der Konferenz von Messina benannten Bereiche geht.

From 27 to 29 April 1956, at the end of its meeting in Paris, with the help of the Socialist Movement for the United States of Europe (SMUSE), the European Congress of Labour — attended by Paul-Henri Spaak, Sicco Mansholt, Guy Mollet and Jean Monnet — adopts a series of resolutions on the social objectives of the future European Economic Community (EEC).

On 12 October 1956, the International Confederation of Christian Trade Unions (ICCTU) forwards to the Foreign Ministers of the six countries participating in the Intergovernmental Conference held at the Château de Val Duchesse a memorandum in which it emphasises the importance of involving workers in developments in the Common Market as well as the peaceful nature of Euratom.

In November–December 1956, 13 European trade unions send a letter to the chairman of the Brussels Conference and to the foreign ministers of the participating countries in which they emphasise their commitment to the social aspects of the Common Market and Euratom and request that the treaties being drawn up provide for the legitimate participation of trade unions.

On 10 December 1956, Hendrik Oosterhuis, Chairman of the Dutch Trade Union Federation and member of the Action Committee for the United States of Europe (ACUSE), sends a letter to the Foreign Ministers of the six countries participating in the Intergovernmental Conference on the Common Market and Euratom in Val Duchesse in which he emphasises the importance that he places on the association of European trade unions with the operation and social aspects of the future European Economic Community (EEC) and European Atomic Energy Community (EAEC or Euratom), in particular through the establishment of an Economic and Social Committee (ESC).

On 24 January 1957, Robert Bothereau, Secretary-General of the General Confederation of Labour-Workers’ Force (CGT-FO), stresses the importance of the future European Economic Community (EEC) and Euratom and emphasises the place of the trade unions in the structures of the two Communities.

„Ein gemeinsamer Markt? Einverstanden, aber nur unter uns.“ Am 24. Januar 1957 kritisiert der französische Karikaturist Nitro in der Wochenzeitschrift des Allgemeinen Gewerkschaftsbundes-Force ouvrière (CGT-FO) die Politik der deutschen und französischen Arbeitgeber, die versuchen, die Arbeitnehmer von den Verhandlungen und der Gründung der Europäischen Wirtschaftsgemeinschaft (EWG) auszuschließen.

Am 25. Januar 1957 veröffentlicht die luxemburgische Gewerkschaftszeitung Sozialer Fortschritt eine Stellungnahme des Internationalen Bundes der Christlichen Gewerkschaften (IBCG) zum Gemeinsamen Markt und Euratom.

On 25 January 1957, the Dutch Liberal daily newspaper Nieuwe Rotterdamse Courant publishes a statement made by the trade unionist Louis Major, Secretary-General of the General Federation of Belgian Labour (FGTB) and Socialist MP, who speculates about the social aspects of the future European Economic Community (EEC).

On 30 January 1957, the Netherlands free trade unions state their position on the draft Treaty establishing the European Economic Community (EEC).

Am 7. Februar 1957 betont die luxemburgische sozialistische Tageszeitung Tageblatt erneut die Notwendigkeit für die Sozialisten und die Gewerkschaften, bei den Vorbereitungen des Vertrags zur Gründung der Europäischen Wirtschaftsgemeinschaft (EWG) darauf zu achten, die Interessen der Arbeitnehmer zu verteidigen.

Am 21. Februar 1957 veröffentlicht die luxemburgische Gewerkschaftszeitung Sozialer Fortschritt ein Memorandum des Bundes der Christlichen Gewerkschaften über die wirtschaftlichen und sozialen Herausforderungen der Verträge zur Gründung der Europäischen Wirtschaftsgemeinschaft (EWG) und der Europäischen Atomgemeinschaft (EAG oder Euratom).

Im April 1957 begrüßt die deutsche Gruppe der Europäischen Vereinigung für wirtschaftliche und soziale Entwicklung die Unterzeichnung des Vertrags zur Gründung der Europäischen Wirtschaftsgemeinschaft (EWG) in Rom und erinnert an die notwendigen Voraussetzungen für dessen Umsetzung.

On 11 April 1957, welcoming the signing on 25 March 1957 in Rome of the Treaties establishing the European Economic Community (EEC) and the European Atomic Energy Community (EAEC or Euratom), Raymond Le Bourre, Confederal Secretary of the Workers’ Force Confederation (FO), emphasises that the working class must participate in the European integration process.

At the Congress of the World Federation of Trade Unions, held in Leipzig from 4 to 15 October 1957, Benoît Frachon, French General Secretary of the General Confederation of Labour (CGT), delivers an address in which he outlines the dangers of the Common Market.

On 8 December 1957, in an article published in the French daily newspaper Le Monde, Otto Brenner, leader of the West German Metalworkers’ Union and Member of the Action Committee for the United States of Europe (ACUSE), criticises the lack of representation of trade union organisations in the institutions of the European Economic Community (EEC) and the European Atomic Energy Community (EAEC or Euratom).

In June 1956, at the third international conference organised in Brussels by the European League for Economic Cooperation (ELEC) on the economic issues surrounding the European revival, Rudolf Meimberg, professor at the University of Frankfurt and Director of the Deutsche Bank, outlines the advantages of a European common market and a customs union, particularly with regard to their social aspects.

In June 1956, the European League for Economic Cooperation (ELEC) holds its third international conference in Brussels. At the conference, Geldofph A. Kohnstamm, who works for the Arnhem-based company Algemeene Kunstzijde Unie, presents an introductory report in which he considers the possible consequences of the Common Market for the social development of European citizens.

On 6 September 1956, Maurice Faure, Junior Minister in the French Foreign Ministry and Head of the French Delegation to the Intergovernmental Conference on the Common Market and Euratom, outlines to the other national delegations present at the Château de Val Duchesse France’s position on the harmonisation of social policies and systems within the Common Market.

En 1955, le Bureau international du travail (BIT) charge un groupe d'experts d'étudier les aspects sociaux de la coopération économique européenne. Un an plus tard, les experts rendent publiques leurs conclusions.

On 1 October 1956, the Dutch Council of Ministers examines the social demands made by the French delegation to the Intergovernmental Conference on the Common Market and Euratom.

On 14 December 1956, the European League for Economic Cooperation (ELEC) adopts a resolution in order to express its support for improvements to social security through the establishment of a common market in Europe.

Am 19. Januar 1957 bedauert die deutsche Wirtschaftszeitung Der Volkswirt, dass die Arbeiten der Regierungskonferenz für den Gemeinsamen Markt und Euratom ihrer Ansicht nach unter zu großer Geheimhaltung verlaufen, und weist auf die Schwächen des Vertrags über die zukünftige Europäische Wirtschaftsgemeinschaft (EWG) vor allem bei den Maßnahmen zur Harmonisierung der Sozialsysteme hin.

In March 1957, La Revue Politique, the official publication of the Belgian Social Christian Party (PSC), looks at the provisions in the Treaty establishing the European Economic Community (EEC) regarding the harmonisation of salaries and social security contributions.