Can it be done?

[BulletH0l3s]

Okay, I was just looking through the guide and it didn't mention this, but can I play through the entire game in co-op and we both get the "Complete on ______" achievements?

[WackFiend]

No. The achievement states "Complete the Solo Missions". Otherwise, you could just play co-op with a second controller and just have it be a respawn point.