51 Achievements
Air Show Perform 2 aerial gestures before touching the ground in co-op
471 achievers
Asking for Trouble Taunt GLaDOS in front of a camera in each of the five co-op courses
201 achievers
Bridge Building Complete all test chambers in the Hard-Light Surfaces co-op course
407 achievers
Bridge Over Troubling Water Complete the first Hard Light Bridge test
733 achievers
Can't Touch This Dance in front of a turret blocked by a hard light bridge in co-op
237 achievers
Confidence Building Complete all test chambers in the Mass and Velocity co-op course
503 achievers
Door Prize Examine all the vitrified test chamber doors
195 achievers
Drop Box Place a cube on a button without touching the cube
480 achievers
Dual Pit Experiment Do the same test twice
587 achievers
Empty Gesture Drop your co-op partner in goo while they are gesturing by removing the bridge under them
132 achievers
Final Transmission Find the hidden signal in one of the Rat Man's dens
186 achievers
Four Ring Circus Enter 4 different portals without touching the ground in co-op
112 achievers
Friends List With Benefits While playing co-op, hug 3 different people on your friends list
100 achievers
Gesticul-8 Perform all 8 gestures of your own volition in co-op
349 achievers
Good Listener Take GLaDOS' escape advice
471 achievers
High Five Celebrate your cooperative calibration success
675 achievers
Iron Grip Never lose a cube in Chamber 6 of the Mass and Velocity co-op course
95 achievers
Lunacy That just happened
564 achievers
Narbacular Drop Place a portal under your co-op partner while they are gesturing
166 achievers
No Hard Feelings Save a turret from redemption
538 achievers
Obstacle Building Complete all test chambers in the Excursion Funnels co-op course
343 achievers
Overclocker Complete Test Chamber 10 in 70 seconds
140 achievers
Party of Three Find the hidden companion cube in co-op test chamber
111 achievers
Pit Boss Show that pit who's boss
228 achievers
Portal Conservation Society Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements
84 achievers
Portrait of a Lady Find a hidden portrait
248 achievers
Preservation of Mass Break the rules in Test Chamber 07
512 achievers
Professor Portal After completing co-op, complete Calibration Course online with a friend who hasn’t played before
107 achievers
Pturretdactyl Use an Aerial Faith Plate to launch a turret
226 achievers
Rock Portal Scissors Win 3 co-op games of rock-paper-scissors in a row
219 achievers
SaBOTour Make a break for it
673 achievers
Scanned Alone Stand in a defective turret detector
513 achievers
Schrodinger's Catch Catch a blue-painted box before it touches the ground
160 achievers
Ship Overboard Discover the missing experiment
262 achievers
Smash TV Break 11 test chamber monitors
111 achievers
Stalemate Associate Press the button!
668 achievers
Still Alive Complete Course 4 with neither you nor your co-op partner dying
47 achievers
Stranger Than Friction Master the Propulsion Gel
605 achievers
Talent Show Never lose a cube in Chamber 6 of the Mobility Gels co-op course
57 achievers
Tater Tote Carry science forward
615 achievers
Team Building Complete all test chambers in the Team Building co-op course
583 achievers
The Part Where He Kills You This is that part
565 achievers
Triple Crown Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
77 achievers
Tunnel of Funnel Master the Excursion Funnel
563 achievers
Undiscouraged Complete the first Thermal Discouragement Beam test
813 achievers
Vertically Unchallenged Master the Repulsion Gel
638 achievers
Wake Up Call Survive the manual override
863 achievers
White Out Complete the first Conversion Gel test
592 achievers
You Made Your Point Refuse to solve the first test in Chapter 8
236 achievers
You Monster Reunite with GLaDOS
823 achievers
You Saved Science Complete all test chambers in all courses of co-op
299 achievers