51 Achievements
Air Show Perform 2 aerial gestures before touching the ground in co-op
499 achievers
Asking for Trouble Taunt GLaDOS in front of a camera in each of the five co-op courses
213 achievers
Bridge Building Complete all test chambers in the Hard-Light Surfaces co-op course
429 achievers
Bridge Over Troubling Water Complete the first Hard Light Bridge test
782 achievers
Can't Touch This Dance in front of a turret blocked by a hard light bridge in co-op
252 achievers
Confidence Building Complete all test chambers in the Mass and Velocity co-op course
533 achievers
Door Prize Examine all the vitrified test chamber doors
208 achievers
Drop Box Place a cube on a button without touching the cube
509 achievers
Dual Pit Experiment Do the same test twice
618 achievers
Empty Gesture Drop your co-op partner in goo while they are gesturing by removing the bridge under them
141 achievers
Final Transmission Find the hidden signal in one of the Rat Man's dens
199 achievers
Four Ring Circus Enter 4 different portals without touching the ground in co-op
120 achievers
Friends List With Benefits While playing co-op, hug 3 different people on your friends list
103 achievers
Gesticul-8 Perform all 8 gestures of your own volition in co-op
372 achievers
Good Listener Take GLaDOS' escape advice
504 achievers
High Five Celebrate your cooperative calibration success
714 achievers
Iron Grip Never lose a cube in Chamber 6 of the Mass and Velocity co-op course
103 achievers
Lunacy That just happened
595 achievers
Narbacular Drop Place a portal under your co-op partner while they are gesturing
176 achievers
No Hard Feelings Save a turret from redemption
566 achievers
Obstacle Building Complete all test chambers in the Excursion Funnels co-op course
366 achievers
Overclocker Complete Test Chamber 10 in 70 seconds
151 achievers
Party of Three Find the hidden companion cube in co-op test chamber
117 achievers
Pit Boss Show that pit who's boss
242 achievers
Portal Conservation Society Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements
87 achievers
Portrait of a Lady Find a hidden portrait
265 achievers
Preservation of Mass Break the rules in Test Chamber 07
541 achievers
Professor Portal After completing co-op, complete Calibration Course online with a friend who hasn’t played before
110 achievers
Pturretdactyl Use an Aerial Faith Plate to launch a turret
246 achievers
Rock Portal Scissors Win 3 co-op games of rock-paper-scissors in a row
228 achievers
SaBOTour Make a break for it
714 achievers
Scanned Alone Stand in a defective turret detector
541 achievers
Schrodinger's Catch Catch a blue-painted box before it touches the ground
174 achievers
Ship Overboard Discover the missing experiment
281 achievers
Smash TV Break 11 test chamber monitors
120 achievers
Stalemate Associate Press the button!
707 achievers
Still Alive Complete Course 4 with neither you nor your co-op partner dying
49 achievers
Stranger Than Friction Master the Propulsion Gel
639 achievers
Talent Show Never lose a cube in Chamber 6 of the Mobility Gels co-op course
59 achievers
Tater Tote Carry science forward
650 achievers
Team Building Complete all test chambers in the Team Building co-op course
613 achievers
The Part Where He Kills You This is that part
596 achievers
Triple Crown Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each
82 achievers
Tunnel of Funnel Master the Excursion Funnel
594 achievers
Undiscouraged Complete the first Thermal Discouragement Beam test
867 achievers
Vertically Unchallenged Master the Repulsion Gel
677 achievers
Wake Up Call Survive the manual override
922 achievers
White Out Complete the first Conversion Gel test
625 achievers
You Made Your Point Refuse to solve the first test in Chapter 8
249 achievers
You Monster Reunite with GLaDOS
875 achievers
You Saved Science Complete all test chambers in all courses of co-op
320 achievers