Both AA and Alitalia are mainline airlines and will (or at least should) have an interline baggage agreement. That means that they will automatically transfer your bags from one airline to the other.

Just make sure that when you check in at Boston your bags are tagged all the way to Rome.

Since you bought the ticket as a single ticket then you are protected in case you miss your connection. Who exactly you deal with I'm not sure. I'd start with Alitalia since they are the ones who will carry you to Rome. Make sure you have local contact # for ORbitz in case you need to reach them in London.

First you need to contact the airlines directly and ask if Amerian & Alitalia have a baggage arrangement so you luggage can be checked thru to your final destination. As long as you do not have to reclaim your bag you would not have to worry about customs.

If it's on one ticket, your bags will be transferred to the Alitalia flight. At Heathrow, just follow the signs to "flight connections" where you'll get on a bus and be taken to T4. Once there, you'll go through security (hand-carry x-ray, metal detector etc.) and be released into the departures area/shopping mall. If you don't have a boarding pass for the next flight (probably you won't) then you should stop at the Alitalia counter on arriving at T4 to obtain it. 2h 15 min. should be enough time for all of this (if it wasn't "legal" then Orbitz couldn't sell you the ticket) but I wouldn't dally around.

Hold on... you said Terminal 5 to Terminal 4? If that's the case, then you aren't riding American to London, you're riding on British Airways, albeit probably with an American flight number - called a "codeshare." Look carefully at your ticket and see if it reads something like "Operated by British Airways" for the BOS-LHR leg. It should, because AA uses Terminal 3 at Heathrow, not T5.

Shouldn't make any difference in terms of the transfer; just make sure when you check in at Boston (you check in with the operating airline, in this case BA if I'm right) that your bags are tagged through to Rome/FCO.

In the event of a delay, it's typically up to the airline that caused the delay to make it good. Unfortunately, Orbitz' reputation at working out kinks in tickets they've sold is not the best, but it sounds like you're through with the process, so it's up to the fates. There are plenty of flights daily between London and Rome, so you should be okay with getting a later Alitalia flight if things go sideways.

Well if the ticket wasn't already purchased, I would encourage you to book directly with the airlines, not thru Orbitz because I think you have more consumer-power that way in case of delay, etc. There is no "Orbitz" counter at an airport like there are BA, American, or Alitalia.

Gardyloo, thank you and you are correct. My confirmation says American Airlines but then in faint print at the bottom it says operated by British Airways.So in Boston, I check in with BA, correct? (What does American have to do with this reservation then)? And do I follow the baggage policy of AA or BA in this situation? Thank you kindly for the previous information.

Oh, I'm sorry. I see you already answered the question of which airline to check in with from Boston. Again, thank you.

What does American have to do with this reservation then)? And do I follow the baggage policy of AA or BA in this situation?

Airlines that are partners sometimes allow each other to sell tickets for flights operated by the other partner. In this manner they can share revenue for the flights, which helps their bottom lines; also there are cases where frequent flyers get better/different benefits by using one airline's flight number vs. another's, and so on. This is called "codesharing" and it can be confusing to passengers who aren't used to this mechanism. In fact, since AA, BA and Iberia were granted anti-trust indemnity a couple of years ago, you'll see that virtually all transatlantic flights operated by any of those three airlines carry separate flight numbers - one for each of the partners - even though only one of them is actually doing the flying.

When you encounter this (and it's not just AA/BA/IB that do it - it happens all over the industry) the rule is that you always check in at the operating airline's counters, and you're bound by the baggage and seating policies of the operating airline. In your case, because it's an AA flight number on a BA plane, you'll be bound by BA's rules regarding cabin baggage, seat selection (i.e. you have to pay for advance seat choices on BA planes but not on AA) and all that.

You will also have a separate BA reservation locator, which you'll need to get from either BA or AA, probably over the phone. It's important that you have this so that, if you don't want to pay for advance seat selection, you can still log onto BA's website 24 hours before your flight and use the "manage my booking" feature to pick your seats then.

AA's record locator code (NOT Orbitz') will be six letters, like ABCDEF. BA's will have a combination of six letters or numbers, like ABC2DE. It's the BA code that will matter when you check in, so you might as well get it asap.

Thank you so much you have been tremendously helpful

I've found the Heathrow website to be helpful too in terms of information for terminal transfers. Although perhaps not as considerately answered as Gardyloo!