Climate change is increasingly altering the pattern of climate-related risks. Developing countries, and in particular least developed countries, will be among the most severely impacted by climate change. The challenge for planners and policy-makers today is that it is impossible to predict with certainty the future conditions to which adaptation is needed. This paper sets out simple, practical principles that aim to reduce the impact of uncertainty on decision-making. It also draws out three interconnected messages for decision-makers. Firstly, for adaptation to be effective, comprehensive and implemented at the appropriate scale, it is crucial to integrate adaptation planning within existing priorities, planning processes and policymaking. Secondly, adaptation strengthens the case for pushing ‘faster and harder’ on development priorities. Finally, through building flexibility into adaptation strategies from the outset, climate resilience even under deep uncertainty should be no more challenging than other areas of policy. A central principle in managing uncertainties is to focus on promoting good development and long-term adaptive capacity while avoiding inflexible decisions that could lock-in future climate risk in the long term.