Power Armor Training/Fallout: New Vegas

Power Armor Training is a perk in Fallout 3 and Fallout: New Vegas.

Fallout 3
This perk allows one to use any kind of power armor in the game. Prior to this perk, equipping power armor was impossible. This perk can be gained by two ways:
 * 1) After gaining permission from Elder Lyons, speak to Paladin Gunny in the A-Ring of the Citadel. There is no charge or other requirement for training - the screen simply fades to black as Gunny begins teaching you. Once that's done, you may use any kind of power armor, including the Enclave and the Outcast variants. If you do not ask for training on your own, you will get it automatically at the end of The American Dream when you become an honorary member of Lyons' Pride, however these options appear very late in the game.
 * 2) You automatically gain this perk when you finish the Anchorage Reclamation simulation in the Operation: Anchorage add-on.

Fallout: New Vegas
As in Fallout 3, this perk allows one to utilize power armor. Without this perk, any power armor found cannot be equipped. There are two ways of obtaining this training.
 * 1) After completing the quest Still in the Dark return to either Nolan McNamara or Edgar Hardin, depending on who is now Elder.
 * 2) If McNamara remains Elder, wait 24 hours outside of the bunker for the lockdown to be lifted, then talk to him. Tell him you wish to join the Brotherhood of Steel and this will begin the Eyesight to the Blind quest. When this is completed you will then receive Power Armor Training.
 * 3) If you helped Hardin become Elder, complete the Tend to Your Business quest.
 * 4) The other option for training is to complete the For Auld Lang Syne quest, given by Arcade Gannon. Once you have gathered the Remnants together, you will be provided with the perk in addition to a suit of Remnants power armor.