The U.S. has set as a national goal the narrowing of the achievement gap between lower income and middle-class students, and that between racial and ethnic groups. This is a key purpose of the No Child Left Behind act, which relies primarily on assessment to promote changes within schools to accomplish that goal. However, out-of-school factors (OSFs) play a powerful role in generating existing achievement gaps, and if these factors are not attended to with equal vigor, our national aspirations will be thwarted. This brief details six OSFs common among the poor that significantly affect the health and learning opportunities of children, and accordingly limit what schools can accomplish on their own: (1) low birth-weight and non-genetic prenatal influences on children; (2) inadequate medical, dental, and vision care, often a result of inadequate or no medical insurance; (3) food insecurity; (4) environmental pollutants; (5) family relations and family stress; and (6) neighborhood characteristics. These OSFs are related to a host of poverty-induced physical, sociological, and psychological problems that children often bring to school, ranging from neurological damage and attention disorders to excessive absenteeism, linguistic underdevelopment, and oppositional behavior. Also discussed is a seventh OSF, extended learning opportunities, such as preschool, after school, and summer school programs that can help to mitigate some of the harm caused by the first six factors.