This article explores Head Start's overall effectiveness in improving school readiness and its potential to reduce gaps in light of changes in program goals and in resource and funding capacity, and demographic shifts in the low-income child population it serves. Although not an explicit goal of the program, we assess its ability to reduce school readiness gaps between children of different racial and ethnic backgrounds and income groups. Because of changing policy priorities and Head Start's effort to target vulnerable groups of children with diverse needs, meeting Head Start goals within funding constraints can be challenging. However, we will show in this paper that the program has successfully adapted to its changing environment. Despite the evolving nature of its goals, it has managed to demonstrate a favorable impact on children. In order to evaluate the program's effectiveness in improving school readiness and the potential to reduce inequities in these outcomes, we follow a three-step process of policy assessment. The first section of this article describes Head Start's program logic. This includes the outcomes that the program is designed to address, the specific goals that have been set, and the services intended to address these target outcomes. We begin by describing trends in school readiness and the gaps between children of different racial and ethnic backgrounds and income groups. We then turn to Head Start's current services and highlight what new components have been added. In the second section, we analyze the program's capacity to meet its goals, considering factors such as limited resources, the targeted enrollment of vulnerable subgroups, the establishment of program standards, and the monitoring of quality. Lastly, we define program effectiveness and review the large body of evaluation evidence to understand how effective Head Start has been in meeting the newest goal of improving school readiness as well as its potential to reduce racial/ethnic and socioeconomic achievement gaps. (author abstract)