The Mazzini Society was an antifascist political association, formed on a democratic and republican basis, situating itself within the tradition of the Risorgimento, and created in the United States by Italian-American immigrants in the late 1930s. It was named after Giuseppe Mazzini, a leading figure of Italian reunification in the mid-19th century, who had worked from exile.
The Mazzini Society was founded by Gaetano Salvemini in Northampton, Massachusetts, on September 24, 1939; later on the journalist Max Ascoli became the president. Among its organizers was a group of republicans belonging to the antifascist resistance movement Giustizia e Libertà. Besides Ascoli and Salvemini, there were Tullia Calabi, Lionello Venturi, Michele Cantarella, Roberto Bolaffio, interim president Renato Poggioli, Giuseppe Antonio Borgese, and Carlo Tresca. Its newsletter was the periodical Mazzini News and later Nazioni unite ('Nations united').
With the German occupation of France in June 1940 many Italian antifascists, exiled beyond the Alps, were forced to emigrate again; they found refuge in the United States. Many of them joined the Mazzini Society: Aldo Garosci, Alberto Cianca, and Alberto Tarchiani, who came from Giustizia e Libertà; Randolfo Pacciardi, the political secretary of the Italian Republican Party, who founded the Mazzinian weekly periodical La Giovine Italia in Paris in 1937; and the former foreign minister Carlo Sforza, who had belonged to the short-lived antifascist Unione Democratica Nazionale party and worked at La Giovine Italia under Tarchiani's direction.