Quote Originally Posted by Activision
Welcome to the official breakdown of how player progression will work in Call of Duty: Modern Warfare.

“I was just a "Leftenant" back then...doing some wetwork…” – Captain Price.
Call of Duty: Modern Warfare is set to offer a fresh progression system that gives players a constant stream of rewards while keeping the satisfaction and pride that comes with ranking up.
In Modern Warfare, you will unlock loadout options, Killstreaks, and Field Upgrades through an initial series of Enlisted Ranks, earn permanent rewards and icons through Seasonal Officer Ranks which are memorialized permanently, and unlock an arsenal of attachments and camos through Weapon Levels.
Here is an in-depth look at how this progression system will work:

The Enlisted Ranks: Unlocking Elements of Multiplayer

Ranking Up: Gaining XP

The Officer Ranks: Seasonal Rewards and Badges of Honor

The Player Level: Your Overall Accomplishments

Challenge Missions: Another Way to Rank Up & Earn Cool Rewards

A Full Arsenal: Weapon Experience

Ready for Enlistment? Here’s a Recap
Feature: Explaining Player Progression in Call of Duty®: Modern Warfare®