This paper attempts to answer the question: Who is most vulnerable to declines in welfare during a macroeconomic shock? After clarifying the difference between poverty and vulnerability, an analytical framework is presented and then applied to household panel data from Peru. Major findings are: (a) households with better educated heads are less vulnerable; (b) female headed households are not more vulnerable to declines than male headed households; (c) households with more children are more vulnerable to macroeconomic shocks; and (d) transfer networks that may assist the poor in relatively stable periods do not appear to protect them during a major shock, with the exception of transfers that originate from outside Peru.