It is widely accepted that the level of family economic resources is important for child welfare – even when these resources are well above subsistence levels. However, there is continuing debate both about the mechanisms by which these resources influence child welfare, and about the best way to measure the economic resources of most relevance to children. The latter issue, which is the focus of this report, is most keenly debated in the poverty measurement literature – though many of the issues considered in this debate are equally relevant to wider measures of well-being. Most empirical economic studies of poverty in rich nations define poverty as living in a household with a particularly low income. However, recent decades have seen a number of alternative conceptions of poverty and disadvantage advanced to challenge this conventional approach. These alternatives have been motivated partly by the perceived measurement problems associated with these conventional measures, but also by concern over the political salience of an arbitrary poverty threshold based on a purely economic measure of welfare.