This thesis analyses how transport policy at different levels of governance is responding to sustainability challenges and how such policies can be strengthened, particularly for climate change mitigation in the ASEAN region. Its academic contribution comprises the application of transition studies and policy studies to low-carbon transport and sustainable development. The main conclusions are: 1) The Avoid – Shift – Improve approach needs to be expanded with Access, Lifestyle and Transition considerations in order to be an effective framework that does justice to the distributional, systemic and behavioural aspects of low-carbon transport policy; 2) The newer international climate instruments, such as NAMAs, NDCs and the GCF, show more potential than the Kyoto Protocol instruments to promote sustainable, low-carbon transport, as they are better aligned to national circumstances and better suited to address the barriers that developing country policymakers face; 3) ASEAN instruments around transport focus on policy cooperation and reflect ‘networked regionalism’. Sustainable transport has played a relatively small role in ASEAN cooperation but this role is growing, and a range of ‘soft’ measures can be used to further promote low-carbon transport in its member countries; 4) At the national level, transport policy objectives support international sustainable development and climate goals, however the instruments, mechanisms and calibrations need to be strengthened to reach those objectives. Climate change has, in a few cases, led to policy windows for modifying transport policy; 5) At the local level, Southeast Asian cities such as Bangkok and Manila increasingly recognise the potential and benefits of cycling, yet much remains to be done in policy and planning to move cycling beyond a niche activity. ________________________________________