It is widely agreed that small island developing states (SIDS), a distinct group of 58 developing countries, are uniquely vulnerable to the impacts of climate change. Many SIDS recognize that adequate and effective adaptation to climate change are important components of sustainable development and, as such, are pursuing climate change adaptation policies and programs at the national level. Chapter 29 (Small Islands) of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change suggests that more needs to be learnt about how climate change mainstreaming can be practically achieved in these countries. Working within a resilience framework and interviewing senior government and regional organization officials from Caribbean and Pacific SIDS, this paper aims to understand the drivers of, and barriers to adaptation mainstreaming at the national level. In doing this, it finds multiple drivers – the three most commonly reported are institutional/organizational, ‘champions’/personalities/informal networks and risk and exposure. It also finds multiple barriers – the three most commonly reported are competing development priorities, poor planning/governance and insufficient manpower/human resources. Building on this knowledge, this paper then proposes a seven-step process towards practically achieving mainstreaming in SIDS, which can be used by national governments and regional organizations to guide their actions in this regard.