This paper will identify the fair level of participation in climate change governance. Effective climate change governance requires collective action amongst multiple types of actors on a global scale. Whilst it is generally considered that issues such as the participation of affected stakeholders are key to the creation of a viable governance architecture, there is little definition of the rules and principles that should define the level of participation in a global climate governance regime. This lack of procedural rules not only raises questions about the suitable level of participation in a climate architecture, but also about which types of actors should be included in such a governance system. Should climate governance institutions include non-state actors such as civil society groups and business coalitions? Should such actors be allowed formal voice in substantive negotiations? This paper will identify which actors should be included in a climate change regime by deriving a principle of procedural justice that can guide the institutional design of climate change governance. The paper will explore whether actors should be involved in a climate change regime on the basis of responsibility for the problem or on the basis of vulnerability to the potential harms that will be created by climate change. The relative merit of this principle of procedural justice will be compared against other criteria that guide the level of participation in climate change architecture, including: environmental effectiveness, legitimacy and substantive justice.