In the early 1980s the world became aware that Iraq was producing and using chemical weapons in its war against Iran. Since then the world has become acutely aware of the threat posed by Weapons of Mass Destruction (WMD). We are now faced with an uncertain world in which there is greater concern about the potential use of chemical or biological weapons by rogue states or terrorist groups. This authoritative account details the persistent efforts made first by the United Nations Secretary-General experts in the 1980s, then by the UN Special Commission (UNSCOM) from 1991 to 1998 and by the United Nations Monitoring and Verification Commission (UNMOVIC) in just over three months from November 2002 to March 2003 and subsequently by the Iraq Survey Group (ISG) to uncover the chemical and biological weapons programmes in Iraq. The absence of stockpiles in Iraq is analysed and key lessons drawn for the prohibition regimes for chemical and biological weapons.