After landing in Italy, if you will be driving it is required that you obtain what is called an International Driving Permit (IDP). The IDP is actually an addition to your US state driver's license and is recognized by many countries all over the world, including Italy. The process to obtain this document is simple and requires no testing, so there is no stress involved.
The American Automobile Association (AAA) issues IDPs in the US but you do not have to be an AAA member to use this service. You will need two passport size photos (which the AAA can provide for a fee), your valid state driver's license, and a form that the AAA office will provide. Your local AAA's website may even have the form on-line. While we downloaded and filled in the form, the office we visited wouldn't accept the online form; we were never clear why, but they hand-wrote the information into their own document.
Take these items to your closest AAA office and they will complete a small threefold document with your photo affixed. The entire process should not require more than 15 minutes. You can also obtain this document via mail if you are already living in Italy legally but you will be at the mercy of the US and Italian mail services. Instructions for this service can be found on the AAA websites.
Since the IDP is a translation of your US driver's license you will need to present both the US drivers license (making sure it has an expiration date beyond one year) and the IDP when driving in Italy. The permit is only valid for a year; according to the Italian laws you are required to obtain an Italian driving license after one year.
You can also bring your pets to Italy and drive with them.