Sixty-seven percent of 18-34-year-old Italians live with their parents, the latest figures from statistics agency Eurostat show, a figure almost 20 points higher than the European average.
Only Slovakian youngsters are more likely to live with mum and dad.
Meanwhile, in northern Europe, the vast majority of young adults live independently; 19.7 percent in Denmark, 34.3 percent in the UK and 34.5 percent in Germany.
Across Europe as a whole, the proportion of youngsters living at home has seen an overall drop since the 2008 recession. But Italy bucks the trend; the percentage has crept up steadily each year, with a notable increase of almost two points between 2014 and 2015.
Particularly notable is the high proportion (50.6 percent) of Italians aged 25-34 who live at home, a figure which has risen from 44 percent in 2011 and is almost 22 points above the European average, behind only Greece (53.4 percent). By contrast, in Denmark, just 3.7 percent of 25-34-year-olds live with their parents, compared to 10.1 percent in France and 39.1 percent in neighbouring Spain.
Italian men are particularly likely to stay in the parental home, accounting for 73.6 percent of the total between 18 and 34.
While high rates of youth unemployment are a likely cause, Eurostat notes that 40.3 percent of the millennials living at home were full-time workers.
Students accounted for 18.8 percent of the total, while 24.3 percent were unemployed.
When The Local spoke to young Italians about the topic last year, economic reasons were the most commonly cited factor - however it was far from the only one.
Italians also tend to graduate later than their European peers, leaving them to fly the nest later. Even when they do graduate, many end up in unpaid internships or jobs paying less than €1,000 per month.
Family is traditionally central to Italian society, and so young Italians are more likely to live with their parents than youngsters in other countries with high youth unemployment, such as Poland and Hungary for example.
And although young Italians were famously branded 'bambiccioni' (big babies) by ex-Italian finance minister Tomasso Padoa-Schiopa in 2007 - a term which has stuck - this characterization may be unfair. Numerous economists have argued that clingy parents are actually to blame for the high rate of young adults living at home.