Here is the full list of all 39 The Medium achievements.
Send Jack's spirit away.
Reach the hotel.
Meet Sadness.
Survive a monstrous encounter.
Experience your first vision of Thomas.
Send the Childeater away.
Find the Red House.
Experience your second vision of Thomas.
Send the Hound away.
Uncover the mystery of the burned down house
Make it through the pump station.
Complete the broken mirror.
Finish the game.
Use Insight for at least 15 minutes.
Find an Echo.
Find all Echoes in a single playthrough.
Reconstruct a Memory Shard.
Reconstruct all Memory Shards in a single playthrough.
Find a page from a mentor's diary.
Find all pages from Richard's diary in a single playthrough.
Find a note from a troubled man.
Find all of Thomas' notes in a single playthrough.
Find a postcard from the groundskeeper.
Find all of Frank's postcards in a single playthrough.
Find an Echo of a mysterious caller.
Find all of Henry's Echoes in a single playthrough.
Spend 10 minutes outside your body.
Escape the creature without alerting it.
Feed the cat in Jack's apartment.
Acquire the razor.
Acquire the bolt cutters.
Use a mirror to cross over.
Inspect 25 objects in a single playthrough.
Inspect 50 objects in a single playthrough.
Inspect 100 objects in a single playthrough.
Defeat the creature in the flooded ruins.
Burn through the moths using Spirit Shield.
Use Spirit Blast to create electricity.
Run 2 kilometers.