Organized unionism emerged in Greece with the creation of the labour centres of Volos (1905) and Larissa (1910). Until then workers' organizations were nothing more than unions of solidarity, like a guild rather than a union, in which employers participated as well as workers.

From 1910 onwards the labour class reinforced its presence. The guilds of Athens and Piraeus supported the coup of the Military League. Generally in this period the liberal legal framework in combination with the overall development of radical ideas and the annexation of the new Greek provinces, and especially of Thessaloniki, where there was already a considerable labour movement, gave a boost to the development of unionism. In 1911, with the labour legislation of the Liberals the first labour associations were established without the participation of employers. It was then that the Labour Centre of Athens, the Labour Centre of Piraeus as well as other labour centres were founded.

In this period the idea of a national labour policy was propagated by Socialist intellectuals as being more effective for the interests of the workers, as well as the establishment of a Socialist party that would be the political instrument of the labour movement.
The governemnt did not oppose this prospect. On the one hand, it believed that a panhellenic organization would facilitate unionism becoming part of the process of urban modernization and also facilitate state control; the government could thus prevent any potential radicalization. The law of 1914 set the legal base for the development of the unionism, allowing some measure of state intevention in this process. On the other hand, the pro-labour policy of Venizelos' governments served the goal of national consent and unanimity before the national goals of irredentism. As early as 1917 the Provisional Government of Thessaloniki encouraged the establishment of the Labour Centre to counter-balance the impact of the Jewish Federation. At the same time an attempt was made to win the favour of the international Socialist and labour movement, in order to reinforce Greek negotiation advantages regarding national claims.