A U.S. family of three living in deep poverty survives on an annual income below $9,276, or less than $9.00 a day per family member. The struggle to raise children on such a meager income is not a rare circumstance among U.S. families, especially those with young children. Currently, 11 percent of young children (0-9 years) live in households with incomes below 50 percent of the federal poverty line (FPL), up from 9 percent in 2008. The percentage of young children in deep poverty varies across the states, from 5 percent in North Dakota to 18 percent in Mississippi, 16 percent in South Carolina, and 14 percent in Kentucky and West Virginia. While the negative effects of poverty on children's early development and long-term school and health outcomes are well documented, less is known about the well-being and family circumstances of young children in the subgroup of families with the scarcest financial resources, especially relative to other income groups. This fact sheet compares the early health, development, and risk characteristics of young children in deep poverty to children in families that are poor, but not deeply poor, and to families that are not poor. These groups, defined by family income, are: (1) Young children in deep poverty (family income is below 50 percent of the FPL); (2) Young children who are poor, but not in deep poverty (family income is 50 percent of the FPL to 99 percent of the FPL); and (3) Young children who are not poor (family income is 100 percent or more of the FPL). This fact sheet provides the following information about young children and families in these groups: (1) Prevalence of children experiencing selected health and developmental conditions; (2) Prevalence of children whose parents have characteristics that pose risks for development; and (3) Prevalence of children whose neighborhoods present challenges to parenting and development. The second section of the fact sheet focuses on young children in deep poverty with and without additional family risk factors. The prevalence of young children with negative mental health and development indicators is compared across deeply poor children whose parents experience fair to poor parent health and other adversities, and children in families without these difficulties. Results reported in this section suggest that even within a vulnerable group--young children in deep poverty--certain family adversities may increase children's risk of poor mental health and development. Results of the descriptive analyses show that on almost every indicator, higher percentages of young children in both poverty and deep poverty have poor outcomes, compared to non-poor children. The biggest differences in the health and development of young children are evident in comparisons of non-poor children with those who are poor and deeply poor. However, young children in deep poverty fared even worse than poor children on several health and development indicators, most notably blood lead levels, obesity, and parents' assessment of whether children are "flourishing," a composite measure reflecting children's curiosity, resilience, affection, and positive mood. Young children in deep poverty also appear to be at higher risk for future health and development problems, based on the presence of family adversities. Compared to young children in poverty, a higher percentage of young children in deep poverty have parents who are experiencing poor or fair health or mental health, frequent parenting stress, and a lack of perceived social support and security in the family's neighborhood. These family adversities have been shown to predict poor health and development outcomes in young children. The results also point to especially vulnerable groups of young children in deep poverty. A higher percentage of deeply poor young children with parents experiencing less optimal health or mental health, or frequent parenting stress, were described by parents as having depression, anxiety, a diagnosed developmental delay, and being at high to moderate risk of developmental delay, compared to deeply poor children whose parents reported greater well-being. In each case, deep poverty coupled with a parent risk factor was associated with poor developmental and mental health outcomes for young children.