The name of San Fratello derives from three pious brothers: Alfio, Cirino and Filadelfo. In their honour a festival is held annually on 10 May. The village was founded in the 11th century by Adelaide del Vasto, the wife of Roger I, a noble of present-day French Normandy who conquered Sicily. She came to Sicily together with colonists. They introduced their Gallo-Italic dialect, which is still spoken in the village. San Fratello is one of the so-called "Oppida Lombardorum" of Sicily, settlements established by the Lombards. In addition to their language, they brought Latin Christianity, which gradually replaced the Greek Byzantine Christianity and Islam.