This paper explores the characteristics and causes of homelessness among poor families with children. In so doing, it attempts to develop a conceptual framework on family homelessness that shifts the dominant focus on individual characteristics or structural factors to consider their combined role in fostering homelessness episodes. Analyzing data from 4,900 poor families in twenty cities who took part in the Fragile Families and Child Wellbeing Study, the authors find that homelessness episodes are more closely linked to mother’s physical health, exposure to domestic violence and social connectedness, as well as housing affordability, local unemployment rates, receipt of housing subsidies, the availability of shelter beds, and anti-homeless laws. However, basic socio-economic and demographic characteristics thought to influence family homelessness were not observed to have any effect, including educational attainment, labor force participation, welfare receipt, martial status, or race. Moreover, poor families living in cities with severe weather, higher housing vacancy rates, and higher poverty rates were not at an increased risk of becoming homeless.