The Caribbean Community Climate Change Centre was launched in 2005, culminating a process that included three precursor projects: Caribbean Planning for Adaptation to Climate Change (1997–2001); Adapting to Climate Change in the Caribbean (2001–2004); and Mainstreaming Climate Change (2003–2009). Each benefited from multiple sources of official development assistance (ODA), clearly defined tasks, and leadership from the region’s scientific and technical communities. Shared goals and principles across the projects included: use of bottom-up participatory methods; building the technical capacity of national and regional institutions; mainstreaming adaptation in economic development programs; and partnering with governmental, non-governmental, and private sector organizations. This article applies concepts from the global environmental politics literature on interplay, environmental policy integration, and regional governance to trace the institutionalization of the Centre. Fifteen semi-structured interviews and reviews of project documents reveal how the Centre built capacity to plan and manage projects, act as a regional hub for technical support and data, participate in the multi-level political interplay required to secure ODA, while exploring other funding sources; and the extent to which it has been able to maintain its commitment to bottom-up, participatory methods, effective internal and external communications, social assessment, and monitoring and evaluation of projects.