This paper challenges the notion that 2003 marks the dividing line between a ‘sectarian’ and a ‘non-sectarian’ Iraq. It begins by outlining how the confused understanding of an as yet undefined but widely used term, namely ‘sectarianism’, has served to blur our understanding of many issues relating to sectarian identities and sectarian relations. Once the definitional issue is addressed we can then discuss sectarian relations in pre-2003 Iraq and the Middle East. The argument will be made that, like many other forms of communal relations, Sunni-Shi’a relations were marked by varying degrees of relevance throughout the 20th century. More importantly, it will be argued that nation building and state building in the modern Middle East have never adequately addressed the fact of sectarian plurality, opting instead for a policy that advocated a unity based on the negation, rather than acceptance, of sectarian identities. Similarly, some sectarian groups – those with an awareness of their sectarian ‘otherness’ such as was commonly found amongst Iraqi Shi’as – often resisted the modern Arab state’s attempts at absorption through dilution in an avowedly a-sectarian model. Crucially, due to socio-historical reasons that will be discussed, this was always less problematic for Sunnis than it was for Shi’as or, to be more precise, for those Shi’as for whom Shi’a identity and Shi’a religious and social structures formed a crucial par of their self-conception. This paper will argue that many of the destructive sectarian dynamics seen since 2003 are the end result of a cumulative process extending far back into the 20th century. Only by understanding the subtleties of sectarian relations in the 20th century – in both their negative and positive aspects – can we understand how a culture of sectarian mobilisation grew in the first place which in turn explains why sectarian forces were best positioned to dominate politics in Iraq in 2003. At heart the issues that have animated these dynamics relate more to modern contentions regarding the state rather than religion or sectarian dogma. In many ways, the Sunni-Shi’a issue in modern Iraq has been animated by divergent views regarding the legitimacy of the state – something that appears more relevant than ever in today’s Iraq.