Roma Pass

As I understand it (open to corrections because I haven't reserved this way in a couple of years), you can make the reservation and tell them that you will use the Roma Pass, then present the Pass when you pick up your ticket.

This was over 2 years ago for us as well (December 2012), but the Galleria didn't process our admission payment until we arrived at their front counter at the appointed time prior to our entry. We showed our Roma passes then, and they charged us the discounted entry fee. We made reservations ahead of time once we were in Italy, but you can call from the US if that works for you. Enjoy - it's spectacular!

Yes, when using the romapass for free admission you must call to make the reservation. Let them know you'll be using the pass for free admission. They will make the reservation and give you a confirmation code. Once you get to the gallery just give them the code and they will look up the reservation. Give them your romapass to scan and you'll be set.

Be sure to arrive at least a half hour before the start time or they can give away your reservation.

Donna

Yes, but as Donna said, you must CALL them; don't try to reserve online. Here's the info (from the Roma Pass website):

"For the Borghese Gallery and Palazzo Valentini (Domus Romane), booking is required also for Roma Pass and/or Roma Pass 48 hours holders. Reservations are not required for any other museums, though it is highly recommended that school or tourist groups make reservations, in order to facilitate entry to museums.
For reservations to the Borghese Gallery and/or Domus Romane/Palazzo Valentini, please call +39 06 32810 (open Monday to Friday, 9:00 am to 6:00 pm – Saturdays, 9:00 am to 1:00 pm). Bookings can be made directly from the visitor’s home country, even before purchasing the card. Please note: it is not possible to make an online reservation without prepaying the ticket. If you intend to visit the museum / site with your Roma Pass or Roma Pass 48 hours, you must make your reservation on the phone, by calling +39 0632810."

Thank you Thank you lovely people. You have been so much help. I am sure I will have more questions before we leave for Italy. I feel secure travelling with your help. Thank you again.

You're welcome!
I forgot to mention that call center hours given in the info from the Roma Pass website are ROME time!

Calling a week in advance is likely to result in frustration.

They don't keep a certain number back for those reservations - when the group is full the group is full. If all the reservations have gone for the day you want, you will miss those incredible statues.

They don't open reservations months ahead, but you are well advised to make your reservation as soon as you can commit to a time when the reservations are open.

It isn't like most places with a flow through of visitors. They admit everybody for the two hour time slot at the same time (maximum 360 people) and at the end of the 2 hours everybody has to leave so the next group can enter.