This report, using empirical evidence from research in Niger and north-east Brazil, aims to identify how climate change adaptation can be integrated within the water sector to benefit the most poor and vulnerable people. It draws on primary research at the community level, and policy and institutional reviews at the national level, to look at: how the changing climate is impacting the way poor people manage their water resources in the semiarid environment, their adaptive responses to climate variability, and associated needs to help support these responses; the policy and institutional context in each country in relation to tackling water and climate change, the current status of synergy and integration between the two policy areas, and the interface between national policy and practice on the ground. The report shows that climate variability can have a real and lasting impact on how people manage their water resources, and that the dynamics of changing patterns of water availability have knock-on effects that reach far beyond just water.