This chapter argues that three key themes of Groupthink affected the US and the UK decision-making processes: mindguarding, a stereotyped view of the enemy, and collective rationalisation. Whilst each of the three themes affected both decision processes, they manifested differently in Washington and London. In the US decision-making group, mindguards focused on establishing a link between Iraq and Al Qaeda, whereas the mindguards in the UK group focused their attention on establishing the legality of military action against Iraq. Both the US and UK groups held the shared stereotyped view of Saddam Hussein that he was adept at “getting away with it”. This stereotyped view framed the perception of all of Saddam Hussein’s actions in the decision-making, reducing the consideration of these actions. However, the US went further, and held an additional stereotyped view that Iraq was linked to Al Qaeda. It was this belief in a relationship existing between Iraq and Al Qaeda that was then collectively rationalised in the US decision-making group, building the confidence of group members in this view. Collective rationalisation is a means to enabling further group cohesion, requiring members to agree to the view being rationalised or leave the group by choice or through ostracisation. In the UK, decision-makers collectively rationalised that military action against Iraq would be legal without a second UN Security Council Resolution, a key focus of the UK mindguards. This collective rationalisation was key to securing the group cohesion, and therefore the groupthink that afflicted decision-making.