Both Lebanon and the Republic of Yemen have witnessed the emergence of coalition government, albeit in very different circumstances. Coalition governments in Lebanon have obeyed to the logic of the politics of sectarianism which devolves power along religious groups. Often times, so-called power-sharing governments have functioned as enforced “marriages of convenience”. In the Yemeni case, coalitions have developed with varying degrees of success in the post-unification period and since the 2011 uprising. While very significant differences characterise both countries, their experiences of coalition government have a surprising amount in common. This paper will present a critical, comparative analysis of coalition government in both which will focus on the role of politicized identity in the trajectory of such governments. The paper will first examine the literature on coalition formation and examine its application to the Middle East with a view to identifying why and how coalitions ‘work’. It will then review the Lebanese and Yemeni experiences of coalition formation with a focus on a number of key questions of relevance to both cases: To what extent have coalitions relied upon the politicisation of sectarianism? What role has been played by external actors? To what extent have coalitions functioned as strategies for the prevention of systemic change? In conclusion the paper will analyse how and why coalition governments have failed in Lebanon and Yemen and will explore the possibility that such failure has been a consequence of what may be understood as ‘adversarial power-sharing’ rather than a positive commitment to shared ideological or political objectives.