Do you need an International Driving Permit for Italy?

Article 135 of the Italian Highway Code (Codice della Strada) requires drivers holding a license issued outside the EU to carry an official translation of that license. An International Driving Permit satisfies that requirement, which is why the US Embassy in Italy advises Americans to obtain one before traveling.

The IDP never replaces your US license. Italian police expect to see both documents together, and an IDP presented on its own is not valid.

Some sources describe the IDP as optional in Italy on the grounds that a sworn Italian translation is an accepted alternative. That is technically true, but a certified translation is slower and more expensive to obtain than a $20 IDP from AAA, so the IDP is the practical choice.

An International Driving Permit is a translation of your licence into a standard multilingual booklet, issued under the 1949 and 1968 road traffic conventions. It is not a licence, and it is never valid on its own: you carry it with your own licence, and police expect to see both.

It is issued against the vehicle classes already on your home licence, and it never adds one. If your licence does not cover motorcycles, an IDP does not let you ride a scooter in Italy; if it does not cover a heavier vehicle, the permit will not cover a camper or a minibus either. The permit restates what you already hold, in a form the local authorities can read.