Based on more than 10,000 media reports, the dossier is the first detailed account of such deaths.
The Iraq Body Count and Oxford Research Group, made up of academics and peace activists, carried out the survey.
The Dossier on Civilian Casualties in Iraq 2003-2005 says 37% of all non-combatant deaths were caused by US-led forces.
Insurgents are said to have caused 9% of the deaths, while post-invasion criminal violence was responsible for another 36%.
