It has been acknowledged that children from poverty begin school missing many of the prerequisites for school success. The 1963 US initiative, Head Start, is the major federal program aimed at providing children in poverty the experiences necessary to start school on an equal footing with their same-age peers. This article uses data from the Early Childhood Longitudinal Study (ECLS) to examine the reading and math assessment scores of Head Start children as compared to their same-age peers at kindergarten entry. The data suggests that while Head Start children score higher than their same-age peers when compared to non-Head Start children from the same socio-economic status, there is still a gap between Head Start children and their peers in schools with higher social economic standing. The article brings an interdisciplinary focus to the issue of how "peer" is defined for disadvantaged children when examining achievement gaps and relative program effectiveness. (Contains 8 tables and 6 figures.)