Polish Socialist Party – Left also known as Young Faction (Polish: Polska Partia Socjalistyczna – Lewica, – Młodzi, or PPS–L) was one of two factions into which Polish Socialist Party divided itself in 1906. Its primary goal was transform Poland into a socialist country, established through proletarian revolution.
Its opposition was the Polish Socialist Party - Revolution Faction (also known as Old Faction – Starzy) which wanted to restore independent Poland, which was envisioned as a representative democracy.
PPS–L for a time gathered most of the former PPS members, but with the failure of the Russian Revolution of 1905 and corresponding revolution in the Kingdom of Poland (1905-1907), it has lost popularity. In 1909 PPS–FR renamed itself back to Polska Partia Socjalistyczna (Polish Socialist Party); the increasingly marginal PPS–L – opposing the First World War and supporting the Russian revolution of 1917 – eventually merged with Social Democracy of the Kingdom of Poland and Lithuania in 1918 to form the Communist Party of Poland.