While the decarbonization of the global economy will bring immense benefits in the aggregate and to many individuals, it will also be disruptive and costly for some, at least in the short term. As these disruptions and costs have become increasingly salient in recent years, there has been an explosion of interest in the climate policy community about how low-carbon transitions can be implemented justly, equitably, and politically smoothly. A key part of what is needed in responding to this growing interest is a better understanding of the suite of ‘transitional assistance policies’ and strategies that can be deployed, alongside or as part of climate change mitigation policies and processes. Responding to this need, we survey a wide, multi-disciplinary literature to answer the ‘who’, ‘what’ and ‘how’ of transitional assistance policy: who is likely to be adversely affected by the low-carbon transition, and in what ways? What substantive strategies and policy instruments are available to governments to mitigate the burdens of low-carbon transitions? And how can governments implement such strategies and policies successfully? In the course of answering the first two of these questions, we develop a novel typology of transitional assistance policies, in which multiple policies are parsimoniously classified according to one of four coherent policy strategies, and one of five kinds of beneficiaries. In answering the third question, we emphasize the importance of certain ‘state capacities’ for shaping transition processes and managing vested interests.