51 Achievements
Air Show Perform 2 aerial gestures before touching the ground in co-op
488 achievers
Asking for Trouble Taunt GLaDOS in front of a camera in each of the five co-op courses
208 achievers
Bridge Building Complete all test chambers in the Hard-Light Surfaces co-op course
420 achievers
Bridge Over Troubling Water Complete the first Hard Light Bridge test
767 achievers
Can't Touch This Dance in front of a turret blocked by a hard light bridge in co-op
245 achievers
Confidence Building Complete all test chambers in the Mass and Velocity co-op course
521 achievers
Door Prize Examine all the vitrified test chamber doors
203 achievers
Drop Box Place a cube on a button without touching the cube
498 achievers
Dual Pit Experiment Do the same test twice
610 achievers
Empty Gesture Drop your co-op partner in goo while they are gesturing by removing the bridge under them
138 achievers
Final Transmission Find the hidden signal in one of the Rat Man's dens
193 achievers
Four Ring Circus Enter 4 different portals without touching the ground in co-op
116 achievers
Friends List With Benefits While playing co-op, hug 3 different people on your friends list
102 achievers
Gesticul-8 Perform all 8 gestures of your own volition in co-op
363 achievers
Good Listener Take GLaDOS' escape advice
493 achievers
High Five Celebrate your cooperative calibration success
701 achievers
Iron Grip Never lose a cube in Chamber 6 of the Mass and Velocity co-op course
100 achievers
Lunacy That just happened
588 achievers
Narbacular Drop Place a portal under your co-op partner while they are gesturing
172 achievers
No Hard Feelings Save a turret from redemption
556 achievers
Obstacle Building Complete all test chambers in the Excursion Funnels co-op course
356 achievers
Overclocker Complete Test Chamber 10 in 70 seconds
147 achievers
Party of Three Find the hidden companion cube in co-op test chamber
115 achievers
Pit Boss Show that pit who's boss
237 achievers
Portal Conservation Society Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements
86 achievers
Portrait of a Lady Find a hidden portrait
257 achievers
Preservation of Mass Break the rules in Test Chamber 07
532 achievers
Professor Portal After completing co-op, complete Calibration Course online with a friend who hasn’t played before
108 achievers
Pturretdactyl Use an Aerial Faith Plate to launch a turret
238 achievers
Rock Portal Scissors Win 3 co-op games of rock-paper-scissors in a row
224 achievers
SaBOTour Make a break for it
701 achievers
Scanned Alone Stand in a defective turret detector
534 achievers
Schrodinger's Catch Catch a blue-painted box before it touches the ground
166 achievers
Ship Overboard Discover the missing experiment
275 achievers
Smash TV Break 11 test chamber monitors
116 achievers
Stalemate Associate Press the button!
695 achievers
Still Alive Complete Course 4 with neither you nor your co-op partner dying
48 achievers
Stranger Than Friction Master the Propulsion Gel
628 achievers
Talent Show Never lose a cube in Chamber 6 of the Mobility Gels co-op course
58 achievers
Tater Tote Carry science forward
638 achievers
Team Building Complete all test chambers in the Team Building co-op course
602 achievers
The Part Where He Kills You This is that part
589 achievers
Triple Crown Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
80 achievers
Tunnel of Funnel Master the Excursion Funnel
587 achievers
Undiscouraged Complete the first Thermal Discouragement Beam test
850 achievers
Vertically Unchallenged Master the Repulsion Gel
665 achievers
Wake Up Call Survive the manual override
903 achievers
White Out Complete the first Conversion Gel test
615 achievers
You Made Your Point Refuse to solve the first test in Chapter 8
244 achievers
You Monster Reunite with GLaDOS
860 achievers
You Saved Science Complete all test chambers in all courses of co-op
310 achievers