One of the themes of La Storia, the account of the immigration of 4.5 million Italians from their homeland to the US (mostly during the late nineteenth and early twentieth centuries), is the reasons for their immigration. The authors note that after Italy was unified in 1871, the south, the Mezzogiorno, suffered as a result of the leaders' indifference to the south. The northern Italians did not understand the southern Italians, and the authors recount the story, possibly apocryphal, of "guffawing northern soldiers who handed out soap to the southern population, only to see the recipients eat it" (xv). The unification of Italy hurt southern Italians, and southern Italians, as a result, comprised 80% of the immigrants to the US (xiv).

Another theme is the poverty that the immigrants faced in the US. As the authors write, "For people who had been steeped in the myth of America all their lives, the first encounters with the promised land were bound to clash with preconceived expectations" (124). In other words, the reality of America, in which immigrants from Italy often lived in poverty, clashed with their expectations of a promised land in which they would live in material comfort and in freedom.

The authors also portray the process of Italian assimilation into American culture. For example, they write about how organized crime and racketeering were not practices of the first generation of Italian immigrants but were of the second generation as they were assimilated into American patterns of crime. In other words, the so-called mafia arose because of immigrants' experience with and assimilation into American culture. The authors also document the ways in which Italians' assimilation into American culture gave rise to Italian American art forms, including music, theater, and writing, and the ways in which Italians sought to better their working conditions by becoming part of American labor unions.