Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Head Hunter (20 points): Take out 20 enemies with a headshot in any mode.
Silent Victory (40 points): Stealth kill 25 enemies.
Snipe Expert (50 points): Snipe 75 enemies in any mode.
Grenade Expert (20 points): Grenade 50 enemies in any mode.
Squad Count (10 points): Take out 10 enemies in any mode.
Company Count (20 points): Take out 100 enemies in any mode.
Battalion Count (50 points): Take out 500 enemies in any mode.
Al Shatar Campaign (25 points): Complete The Liberation of Al Shatar campaign on any difficulty level.
Castle Festunburg Campaign (25 points): Complete The Raid on Castle Festunburg campaign on any difficulty level.
Desperate Measures Campaign (25 points): Complete Desperate Measures campaign on any difficulty level.
Total Victory (100 points): Complete every campaign.
Play Multiplayer (20 points): Complete a Multiplayer Game.
Play all Multiplayer Modes (40 points): Complete a game in all Multiplayer Modes.
First Place (30 points): Place first in a ranked match, all three game types.
Fight the Good Fight (25 points): Place first in a multiplayer game on the losing team.
Good Citizen (20 points): Host active multiplayer games for 20 hours.
Demolitions Expert (25 points): Destroy 25 Targets in Devastation ranked matches.
Heroic Defender (30 points): Save 50 flags in Capture the Flag ranked matches.
Silver Medal (20 points): Capture 25 flags in Capture the Flag ranked matches.
Juggernaut (25 points): Kill 100 enemies in ranked matches.
Whites of Their Eyes (30 points): Kill 10 enemies in a row in a ranked match without dying.
Bomb Squad (30 points): Disarm 50 bombs in Devastation ranked matches.
Barbarians at the Gate Ross (10 points): Complete Barbarians at the Gate with Ross.
Barbarians at the Gate Bull (10 points): Complete Barbarians at the Gate with Bull.
Barbarians at the Gate Taggert (10 points): Complete Barbarians at the Gate with Taggert.
The Hill Ross (10 points): Complete The Hill with Ross.
The Hill Bull (10 points): Complete The Hill with Bull.
The Hill Taggert (10 points): Complete The Hill with Taggert.
Hell from Above Ross (10 points): Complete Hell from Above with Ross.
Hell from Above Bull (10 points): Complete Hell from Above with Bull.
Hell from Above Taggert (10 points): Complete Hell from Above with Taggert.
Ascension Ross (10 points): Complete Ascension with Ross.
Ascension Bull (10 points): Complete Ascension with Bull.
Ascension Taggert (10 points): Complete Ascension with Taggert.
Breakout (15 points): Complete Breakout.
The Net Tightens Ross (10 points): Complete The Net Tightens with Ross.
The Net Tightens Bull (10 points): Complete The Net Tightens with Bull.
The Net Tightens Taggert (10 points): Complete The Net Tightens with Taggert.
Clash of the Titans (15 points): Complete Clash of the Titans.
The Hallowed Halls Ross (10 points): Complete The Hallowed Halls with Ross.
The Hallowed Halls Bull (10 points): Complete The Hallowed Halls with Bull.
The Hallowed Halls Taggert (10 points): Complete The Hallowed Halls with Taggert.
Strategy by the Book Ross (10 points): Complete Strategy by the Book with Ross.
Strategy by the Book Bull (10 points): Complete Strategy by the Book with Bull.
Strategy by the Book Taggert (10 points): Complete Strategy by the Book with Taggert.
Critical Mass Ross (10 points): Complete Critical Mass with Ross.
Critical Mass Bull (10 points): Complete Critical Mass with Bull.
Critical Mass Taggert (10 points): Complete Critical Mass with Taggert.

Additionally, there are two secret achievements, both of which are currently unknown.