The Internationalist Communist Party (French: Parti Communiste Internationaliste, PCI) was a Trotskyist political party in France. It was the name taken by the French Section of the Fourth International from its foundation until a name change in the late 1960s.
The party was founded in March 1944 by the fusion of three Trotskyist groups: the Internationalist Workers Party, the Internationalist Communist Committee and the October group.
After World War Two ended the PCI had expectations of rapid growth and for a time did expand. but that growth was soon ended when a majority of the organisation broke away when a projected fusion with the Socialist Youth federation of the Seine failed to materialise. This led to a series of internal crises and in 1952 the small party split into two rival groups both of which continued to use the same name.