51 Achievements
Air Show Perform 2 aerial gestures before touching the ground in co-op
422 achievers
Asking for Trouble Taunt GLaDOS in front of a camera in each of the five co-op courses
178 achievers
Bridge Building Complete all test chambers in the Hard-Light Surfaces co-op course
370 achievers
Bridge Over Troubling Water Complete the first Hard Light Bridge test
665 achievers
Can't Touch This Dance in front of a turret blocked by a hard light bridge in co-op
217 achievers
Confidence Building Complete all test chambers in the Mass and Velocity co-op course
459 achievers
Door Prize Examine all the vitrified test chamber doors
180 achievers
Drop Box Place a cube on a button without touching the cube
433 achievers
Dual Pit Experiment Do the same test twice
539 achievers
Empty Gesture Drop your co-op partner in goo while they are gesturing by removing the bridge under them
115 achievers
Final Transmission Find the hidden signal in one of the Rat Man's dens
167 achievers
Four Ring Circus Enter 4 different portals without touching the ground in co-op
100 achievers
Friends List With Benefits While playing co-op, hug 3 different people on your friends list
89 achievers
Gesticul-8 Perform all 8 gestures of your own volition in co-op
321 achievers
Good Listener Take GLaDOS' escape advice
433 achievers
High Five Celebrate your cooperative calibration success
608 achievers
Iron Grip Never lose a cube in Chamber 6 of the Mass and Velocity co-op course
85 achievers
Lunacy That just happened
516 achievers
Narbacular Drop Place a portal under your co-op partner while they are gesturing
151 achievers
No Hard Feelings Save a turret from redemption
492 achievers
Obstacle Building Complete all test chambers in the Excursion Funnels co-op course
316 achievers
Overclocker Complete Test Chamber 10 in 70 seconds
130 achievers
Party of Three Find the hidden companion cube in co-op test chamber
99 achievers
Pit Boss Show that pit who's boss
204 achievers
Portal Conservation Society Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements
76 achievers
Portrait of a Lady Find a hidden portrait
230 achievers
Preservation of Mass Break the rules in Test Chamber 07
469 achievers
Professor Portal After completing co-op, complete Calibration Course online with a friend who hasn’t played before
98 achievers
Pturretdactyl Use an Aerial Faith Plate to launch a turret
203 achievers
Rock Portal Scissors Win 3 co-op games of rock-paper-scissors in a row
200 achievers
SaBOTour Make a break for it
616 achievers
Scanned Alone Stand in a defective turret detector
470 achievers
Schrodinger's Catch Catch a blue-painted box before it touches the ground
149 achievers
Ship Overboard Discover the missing experiment
240 achievers
Smash TV Break 11 test chamber monitors
99 achievers
Stalemate Associate Press the button!
611 achievers
Still Alive Complete Course 4 with neither you nor your co-op partner dying
40 achievers
Stranger Than Friction Master the Propulsion Gel
558 achievers
Talent Show Never lose a cube in Chamber 6 of the Mobility Gels co-op course
49 achievers
Tater Tote Carry science forward
565 achievers
Team Building Complete all test chambers in the Team Building co-op course
527 achievers
The Part Where He Kills You This is that part
518 achievers
Triple Crown Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
66 achievers
Tunnel of Funnel Master the Excursion Funnel
519 achievers
Undiscouraged Complete the first Thermal Discouragement Beam test
733 achievers
Vertically Unchallenged Master the Repulsion Gel
588 achievers
Wake Up Call Survive the manual override
776 achievers
White Out Complete the first Conversion Gel test
544 achievers
You Made Your Point Refuse to solve the first test in Chapter 8
217 achievers
You Monster Reunite with GLaDOS
741 achievers
You Saved Science Complete all test chambers in all courses of co-op
272 achievers