The New Agenda Coalition (NAC) has been widely noted for its contribution to 2000 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons. The NAC played a bridge-building role to negotiate a consensus between the nuclear weapons states (NWS) and the non-aligned movement (NAM). While the outcome, document known as the 13 Practical Steps for Nuclear Disarmament is a significant achievement, it is the coalition strategy employed by the middle power states that is the most important contribution to the study of nuclear disarmament diplomacy. This research proposes that middle power states, such as those involved in the NAC, are effective advocates of the emerging international norm of nuclear disarmament when acting in coalition with other like-minded middle powers. This research aims to test the capacity of these states to develop the case for nuclear disarmament, persuasively reject or rebut opposing arguments, and constrain the nuclear policies of more powerful states. This thesis holds that the NAC is one example of a larger trend in international disarmament diplomacy of using middle power coalitions to generate disarmament momentum. The middle power coalition approach is identifiable in nuclear, chemical and biological weapons disarmament efforts as well as in the antipersonnellandmines, small arms and light weapons, and cluster munitions disarmament processes. Martha Finnemore and Katherine Sikkink's 'norm life cycle' in Interna'tional Norm Dynamics and Political Change provides a mechanism which can be use to explain how new international norms can develop and is therefore, an appropriate frame of reference as nuclear disarmament is best characterised as an emerging international norm. Analysis of the case studies is made possible by integrating the outcomes of the theoretical discussion into a template of moderator variables. These variables determine the strength of the relationship between use of the coalition approach and the impact of middle powers as disarmament norm entrepreneurs. Middle power states that employ the coalition approach have adopted a variety of strategies including state-sponsored and state-led efforts, making extensive use of non-governmental partnerships. This research establishes the factors that contribute to successful middle power coalition disarmament advocacy, the international conditions in which these coalitions are likely to be successful and the capacity of the states involved to mitigate and respond to challenges as they present themselves.