Eighty-four percent of U.S. households with children were food secure throughout 2007, meaning that they had consistent access to adequate food for active, healthy lives for all household members. Nearly 16 percent of households with children were food insecure sometime during the year, including 8.3 percent in which children were food insecure and 0.8 percent in which one or more children experienced very low food security--the most severe food-insecure condition measured by the U.S. Department of Agriculture. Numerous studies suggest that children in food-insecure households have higher risks of health and development problems than children in otherwise similar food-secure households. This study found that about 85 percent of households with food-insecure children had a working adult, including 70 percent with a full-time worker. Fewer than half of households with food-insecure children included an adult educated past high school. Thus, job opportunities and wage rates for less educated workers are important factors affecting the food security of children. In 2007, Federal food and nutrition assistance programs provided benefits to four out of five low-income, food-insecure households with children. Appendices include: (1) Questions used to assess the food security of households in USDA's annual food security survey; (2) Findings from selected studies on the effects of food insecurity and food insufficiency on children's health, development, and well-being; and (3) Incidence of food insecurity in selected subpopulations, 2006-07 average. (Contains 15 figures, 7 footnotes, and 5 tables.)