This paper provides a meaning for the term chronic poverty ‘in a nutshell’ and explores the concepts of poverty, vulnerability and poverty dynamics that underpin this meaning. Subsequently, it reviews ‘who’ is chronically poor, ‘why’ they stay poor and what is known about policies to reduce chronic poverty. Despite the limited knowledge available it is clear that hundreds of millions of people are chronically poor, the causes are multifarious but can be analysed through livelihoods frameworks and that the scale and nature of chronic poverty will require an increase in the levels of financing allocated to social protection in developing countries. Recent conceptual and methodological advances, and the increasing availability of panel datasets, mean that the analysis of deprivation can move on from poverty trends to poverty dynamics.