Long after seeing millions of Italians emigrate as they fled poverty and war, Italy has now become a country to which millions of people have migrated, its schools and neighborhoods filling with Africans, Asians, Latin Americans and Eastern Europeans.

Yet many here say the law has not kept up with this dramatic demographic and social change, still making it too hard for immigrants to become Italian.

On Sunday and Monday, Italians will be called to vote in a referendum to decide whether to reduce the legally required residency in the country to five from 10 years in order to be able to apply for citizenship.

A change in the law would allow hundreds of thousands of foreigners to apply for citizenship, and would be a blow to the conservative Prime Minister Giorgia Meloni, who opposes loosening the citizenship law.

But for the referendum to pass, a majority of Italian voters must turn out, with most of them voting “yes.” Many observers are skeptical that will happen in a country where turnout is low.

Whether it passes or not, the referendum has already succeeded in raising important questions about who can be a citizen at a time when migration has set off debate in the United States and Europe.