plane transfers in Europe

Since you're flying on a single ticket, your bags will be checked through to your final destination. You won't have to retrieve them or go through customs (which will probably be a walk through for you) until then. However you will have to go through a passport check at the first airport at which you land.

You will have to claim your bags and clear customs upon arrival in Rome and upon your return in Boston. If you are on a connecting flight out of Rome to say, Frankfurt and are not leaving the secure area of the airport and your baggage is checked through, i.e., Boston-Rome-Frankfurt, then you would claim your bags in Frankfurt and clear customs there. You only clear customs once upon arrival in the EU and once again upon returning to the US from overseas. Don't know if you have to clear passport check in Rome. I don't recall having to do it when I did a transfer in Zurich on a flight out of L.A. but if I did it couldn't have been much of a hassle since I don't remember it. Hope this info helps.

Thanks very much. I had read somewhere that someone had to do customs both places. I will make sure my bags are checked through to destination.

I assume you will change planes in Zurich on your way to Rome. According to the Zurich airport site, you will need to go through passport control and security. You will go through immigration/passport control when you arrive in Rome. Your bags should be checked all the way through to Rome. I assume that you will change planes in either Frankfurt or Munich on your way from Rome to Boston. I didn't check the sites for either connection airport, but I expect that the same thing will apply. Your baggage should be checked all the way through, but you'll have to go through passport control and security. You'll go through customs when you arrive in Boston.