The current official poverty measure compares income to needs within a family. Some have suggested including cohabiting couples as part of this family. Others have suggested that the household be used as the unit of analysis for poverty measurement. I explore issues involved in expanding the unit of analysis, including the stability of cohabiting and other non family household relationships and the degree of resource sharing that takes place among different types of people within households. Instability in households with non family members is not a serious problem for inferring poverty from cross-sectional studies. On the other hand, income from people in non family household roles contributes slightly less to helping other household members avoid financial hardship, implying that non family housemates have a greater tendency to keep income to themselves.