As of 2009,[update] the IMF had more than 200 member organisations in 100 countries, representing a combined membership of 25 million workers.

[2] From 1921, its constitution called for not only international co-operation to improve wages and conditions, but also for workers to take over the means of production.

[3] Membership of the federation reached 1.9 million in 1930, but fell to only 190,000 in 1938, hit by the international depression.

By 1947, membership had reached a new high of 2.7 million, and the federation took a leading role in opposing the World Federation of Trade Unions, instead becoming a founding constituent of the International Confederation of Free Trade Unions.

[3] The organization held a congress every four years, consisting of delegates from the member organisations.