This paper reviews evidence on how risk affects development outcomes at the household level, in particular among the poor, by providing a categorization of the effects of different types of risk on welfare, assets, human capital, and other outcomes at different points in the life cycle, but also the mechanisms through which risk affects these outcomes, offering a comprehensive view of risk, taking into account the multiple shocks that people and communities face, as well as the various ways in which people manage them. Policies need to help the most vulnerable (that is, the poorest) to avoid the costs in human capital that shocks may impose, but interactions between different risks and particular obstacles to managing them often remain unidentified, making it difficult to determine the most effective management tools. Specifically, the degree of complementarity or substitutability between interventions such as cash transfers, infrastructure, and public service provision require better understanding.