It is widely acknowledged that Small Island Developing States (SIDS) are particularly vulnerable to climate change and will continue to require external support to adapt to current and future impacts. The international development community plays an important role in supporting SIDS adapt to climatic changes, and calls for increased international commitment have been made. However, how the vulnerability of SIDS to climate change is being conceptualised and, subsequently, how adaptation programmes are conceived and designed by the international development community are yet to be critically explored. Using Timor-Leste as a case study, this study examines the conceptual trends underpinning 32 donor-led adaptation programmes implemented from 2010 to the present date. Results show that donor-led adaptation programmes continue to conceptualise climate change vulnerability as a biophysical issue rather than a consequence of the dynamic interactions between political, institutional, economic and social structures. Adaptation policy responses therefore have limited ability to target more nuanced and broader-scale structures affecting SIDS and may be falling short in their efforts to reduce the vulnerability of SIDS. We argue that it is critical that the international development community re-conceptualise its approach to vulnerability reduction in SIDS. We conclude by highlighting how the Paris Agreement, with its expanding understanding of vulnerability, can act as a useful instrument to promote such changes.