This article develops a brief screen to identify families at risk for food insecurity (FI) and evaluates the sensitivity, specificity, and convergent validity of the screen.  In a sample of 30,098 families, 23% were food insecure.  The Household Food Security Survey questions 1 and 2 were the most frequently endorsed among food-insecure families (92.5% and 89.1% respectively).  A 2-item FI screen was sensitive, specific and valid among low-income families with young children. The FI screen rapidly identifies households at risk for FI, enabling providers to target services that ameliorate the health and developmental consequences associated with FI.