It is a reading of the Christmas story from the Bible with a choir singing traditional Christmas carols. It's very moving and a reminder of the reason for the season. You do not necessarily need a reservation. It's free to those with park entrance. However, it is very popular and depending on the narrator, extremely popular. There are shows each evening at 5:00, 6:45, and 8:15. The line to get into the open air seating usually starts to form around 3:00, but for some narrators, it will start as soon as WS opens. You can get a Candlelight Processional Dinner Pkg that will guarantee you a seat, but you still need to line up about 45 min before your time. You can also hear and see some just by standing on the walkway behind the theater or sitting at one of the outside tables of Liberty Inn QS dining place.