Call of Duty: Modern Warfare 2 Challenges

Call of Duty: Modern Warfare 2 has many challenges to help you rank up. There are 14 different Categories.

Prestige
These challenges are unlocked after Prestiging once. All of the challenges related to killstreaks carry over into the next levels of prestige, whereas the Heads Up! and the last five challenges (Knife Veteran, Last Stand Veteran, Stealth, Stun Veteran, and Flashbang Veteran) reset after each prestige.

Hidden/Other
These challenges cannot be found in the barracks, but can be completed by playing through multiplayer. These challenges seem to unlock after certain levels, but it is unknown which levels (EG: Radiation Sickness will not unlock until after level 10). Italics mean unconfirmed names, xp or description. Currently, all of these challenges reset when Prestiging.