The CLN was formed on 9 September 1943, following Italy's surrender to the Allies and Germany's invasion of the country. The member parties were the Italian Communist Party, the Italian Socialist Party, the Action Party, Christian Democracy, the Labour Democratic Party, and the Italian Liberal Party. With the backing of the Royal government and the Allied powers, CLN gained official recognition as the representative of the Italian resistance movement, and had several leaders operating underground in German-occupied Italy.
The partisan formations controlled by the CLN were primarily divided between three main groups, Communist Garibaldi Brigades, the Action Party's Justice and Freedom Brigades, and Socialist "Matteotti" Brigades. Smaller groups included Catholic and monarchist partisans. There were partisan units not represented in the CLN, including the Brigata Maiella and anarchist, republican and Trotskyist formations.