51 Achievements
Air Show Perform 2 aerial gestures before touching the ground in co-op
453 achievers
Asking for Trouble Taunt GLaDOS in front of a camera in each of the five co-op courses
189 achievers
Bridge Building Complete all test chambers in the Hard-Light Surfaces co-op course
393 achievers
Bridge Over Troubling Water Complete the first Hard Light Bridge test
704 achievers
Can't Touch This Dance in front of a turret blocked by a hard light bridge in co-op
227 achievers
Confidence Building Complete all test chambers in the Mass and Velocity co-op course
486 achievers
Door Prize Examine all the vitrified test chamber doors
187 achievers
Drop Box Place a cube on a button without touching the cube
462 achievers
Dual Pit Experiment Do the same test twice
565 achievers
Empty Gesture Drop your co-op partner in goo while they are gesturing by removing the bridge under them
124 achievers
Final Transmission Find the hidden signal in one of the Rat Man's dens
176 achievers
Four Ring Circus Enter 4 different portals without touching the ground in co-op
106 achievers
Friends List With Benefits While playing co-op, hug 3 different people on your friends list
92 achievers
Gesticul-8 Perform all 8 gestures of your own volition in co-op
337 achievers
Good Listener Take GLaDOS' escape advice
456 achievers
High Five Celebrate your cooperative calibration success
646 achievers
Iron Grip Never lose a cube in Chamber 6 of the Mass and Velocity co-op course
91 achievers
Lunacy That just happened
542 achievers
Narbacular Drop Place a portal under your co-op partner while they are gesturing
159 achievers
No Hard Feelings Save a turret from redemption
518 achievers
Obstacle Building Complete all test chambers in the Excursion Funnels co-op course
331 achievers
Overclocker Complete Test Chamber 10 in 70 seconds
134 achievers
Party of Three Find the hidden companion cube in co-op test chamber
105 achievers
Pit Boss Show that pit who's boss
219 achievers
Portal Conservation Society Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements
79 achievers
Portrait of a Lady Find a hidden portrait
239 achievers
Preservation of Mass Break the rules in Test Chamber 07
493 achievers
Professor Portal After completing co-op, complete Calibration Course online with a friend who hasn’t played before
102 achievers
Pturretdactyl Use an Aerial Faith Plate to launch a turret
215 achievers
Rock Portal Scissors Win 3 co-op games of rock-paper-scissors in a row
212 achievers
SaBOTour Make a break for it
649 achievers
Scanned Alone Stand in a defective turret detector
495 achievers
Schrodinger's Catch Catch a blue-painted box before it touches the ground
154 achievers
Ship Overboard Discover the missing experiment
251 achievers
Smash TV Break 11 test chamber monitors
102 achievers
Stalemate Associate Press the button!
644 achievers
Still Alive Complete Course 4 with neither you nor your co-op partner dying
43 achievers
Stranger Than Friction Master the Propulsion Gel
583 achievers
Talent Show Never lose a cube in Chamber 6 of the Mobility Gels co-op course
52 achievers
Tater Tote Carry science forward
593 achievers
Team Building Complete all test chambers in the Team Building co-op course
560 achievers
The Part Where He Kills You This is that part
544 achievers
Triple Crown Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
70 achievers
Tunnel of Funnel Master the Excursion Funnel
542 achievers
Undiscouraged Complete the first Thermal Discouragement Beam test
781 achievers
Vertically Unchallenged Master the Repulsion Gel
616 achievers
Wake Up Call Survive the manual override
829 achievers
White Out Complete the first Conversion Gel test
570 achievers
You Made Your Point Refuse to solve the first test in Chapter 8
228 achievers
You Monster Reunite with GLaDOS
791 achievers
You Saved Science Complete all test chambers in all courses of co-op
286 achievers