Children under 10 travel free on public transport services in the territory of Roma Capitale when accompanied by a fare-paying adult.
On Trenitalia vehicles children up to four years of age travel for free as long as they are accompanied by an adult and not occupying a seat. Buggies are admitted for free only if folded. 
On Cotral vehicles, children under 10 years of age travel for free inside the territory of Roma Capitale. Outside the territory of Roma Capitale they travel for free only if they are less than one meter tall, always if accompanied by a paying adult.