Did you ever scream over NKOTB?

Joey McIntyre will help usher in the city's official Christmas tree on Dec. 1.

McIntyre will perform during the pre-lighting ceremony on the Common at 7 p.m. before the tree - an annual gift from Nova Scotia - is switched on. Other performers include American Idol finalist Siobhan Magnus, the Radio City Rockettes, Rockapella, the Boston Ballet, the Boston Children's Choir and saxophonist Grace Kelly.

Mayor Menino, Santa Claus, Deputy Nova Scotia Premier Frank Corbett and some Mounties will throw the switch to light up the 45-foot white spruce donated this year by Ken and Donna Spinney of Central Argyle. The province donates a tree to the city in honor of the medical aid Boston sent to Halifax after an explosion in Halifax harbor in 1917 caused by a collision between two ships, one fully loaded with munitions.