SI is based on the tradition of the British Socialist Workers Party but is not a member of the International Socialist Tendency. SI entered into the Revolutionary Communist League in 2000. The group continues to produce a quarterly journal of the same name.
The people around Socialisme International have notably been active in recent years opposing the ban on the wearing of Muslim headscarves in schools, (along with an alliance of Muslim and Left organizations and individuals) and supporting the idea of a united radical Left candidacy for the presidential elections in 2007.
Combat Comuniste existed for a period but as a tiny grouping, it had many problems and was somewhat heterogeneous which led to its failure. By this point some of the leadership of the group had been won over to the positions of the International Socialists (UK) (as the British SWP was then called). Therefore they sought to win other militants to their views prior to launching an independent group of their own and joined the Ligue Communiste Revolutionnaire (LCR) to further that aim. After a period they were to leave and found the Socialisme International group.
During the 1990s, Tony Cliff, leading theoretician in the British Socialist Workers Party encouraged Socialisme International to follow the successful example of Linksruck (who entered the youth section of the SPD and grew substantially) and join the French Socialist Party. This caused a split, with some leaving entirely and others founding a group called Action, then Action à gauche, and finally Socialisme par en bas.
The group that was left after the split renamed themselves Gauche! and later Socialisme before reclaiming the name "Socialisme International".
In 2000 SI once more joined the LCR. It was followed two years later by "Socialisme par en bas".
Its members are involved in the foundation of a "New anticapitalist party", which is the present policy of the LCR.