This article examines the relationship between Italian immigrants and the labour movement in early twentieth-century San Francisco. It studies the Italians’ integration process through the lens of race by focusing on the racist policies adopted by labour unions, which only admitted “whites” and excluded Asian immigrants. Drawing on a wide variety of sources (the labour press, trade unions’ records, employment data), I will reveal how Italians, although discriminated against and judged as racially inferior, were nonetheless recognised as “white” and therefore assimilated into the labour movement. I argue that this was made possible by the early development of a common “Caucasian” identity among European groups, modelled against Asian immigration, which reduced the tensions that prevailed elsewhere in the United States, namely between the “old stock” and the “new immigrants”, among whom many Italians.