Carlo Alberto Rosselli (16 November 1899 – 9 June 1937) was an Italian political leader, journalist, historian, philosopher and anti-fascist activist, first in Italy and then abroad.

In July 1929 he escaped to Tunisia, from where he travelled to France, and the community of Italian antifascists including Emilio Lussu and Francesco Fausto Nitti.

In 1929, with Cianca, Lussu, Nitti, and a Parisian circle of refugees which had formed around Salvemini, Rosselli helped found the anti-fascist movement "Giustizia e Libertà".

The book was at once a passionate critique of Marxism, a creative synthesis of the democratic socialist revisionism (Bernstein, Turati and Treves) and of classical Italian Liberalism (Benedetto Croce,[4] Francisco Saverio Merlino and Gaetano Salvemini).

It was not surprising, therefore, when one of the most important Italian Communists, Togliatti, defined "liberal Socialism" as "libellous anti-socialism" and Rosselli "a reactionary ideologue who has nothing to do with the working class".

In July 1936, the Spanish Civil War erupted as the fascist-monarchical led army attempted a coup d'état against the republican government of the Popular Front.

With Camillo Berneri, Rosselli headed the Matteotti Battalion, a mixed volunteer unit of anarchist, liberal, socialist and communist Italians.

Speaking on Barcelona Radio in November, Rosselli made famous the slogan: "Oggi in Spagna, domani in Italia" ("Today in Spain, tomorrow in Italy").

After falling ill, Rosselli was sent back to Paris, from where he led support for the anti-fascist cause, and proposed an even broader 'popular front' while still remaining critical of the Communist Party of Spain and the Soviet government of Joseph Stalin.

This work marked Rosselli out as a heretic in the Italian left of his time (for which Karl Marx's Das Kapital, albeit variously understood, was still regarded as the only reliable source of political analysis and guidance).

As a result of the electoral successes of the Labour Party, Rosselli was convinced that the 'norms' of liberal democracy were essential, not only in building Socialism, but also for its concrete realization.

Writing in his final years, Rosselli became more radical in his liberal positions, defending the social organization of the CNT-FAI he had seen in anarchist Catalonia and Barcelona during the civil war, and informed by the rise of Nazi Germany.