Much of the contemporary literature on food security has focused on the rural sector. However, within the current context of high demographic growth, rapid urbanization and rising urban poverty which characterizes much of Sub-Saharan Africa, urban food insecurity cannot continue to be ignored. This study therefore examines the vulnerability of poor households to food insecurity in the challenging urban environment of Harare in Zimbabwe, an acute example of a city (and country) 'in crisis'. Findings from qualitative and quantitative research demonstrate severe food insecurity characterized by critical food shortages and the consumption of narrower diets among poor households in the city. Household vulnerability to food insecurity stemmed from a range of factors, including: high levels of unemployment and poverty; high dependency ratios; low levels of house ownership; hyperinflation; skyrocketing food prices; and the general collapse of the formal food system. Vulnerability to food insecurity was further exacerbated by a prolonged adverse socio-political climate that undermined national economic recovery and reduced the livelihood opportunities available to the urban poor. The paper concludes that in Harare, as in most urban areas of the developing world, the urban poor have become highly vulnerable to food insecurity.