Both the increasing global demand for educated workers and the known importance of early childhood interventions in preparing children—especially those in poverty—for school make early childhood policy a cornerstone of public policy across the globe. Our panel examines the government’s longest-standing intervention in the education of young disadvantaged children—Head Start (HS). Unlike prior work in this area that looks at average treatment effects and subgroup effects, the work of our panel takes a different perspective on the various contexts in which HS is implemented, the mechanisms through which HS operates, and the diverse counterfactuals of HS participants. Our goal is to provide policy researchers with a deeper understanding of how and when this program may affect children’s outcomes. Our studies examine HS and other preschool experiences across five datasets, implementing a range of identification strategies that include randomization, regression discontinuity, principal stratification, propensity scores, and state fixed effects. To examine the effects of HS, it is essential to know how well the program works in comparison to available alternatives. The first paper uses three contemporary datasets to compare school readiness proficiencies between children in Head Start programs and those four comparison groups: prekindergarten, other center-based care, home-based care, and exclusive parental care. They find that the effects of HS can vary drastically across a number of outcomes depending on the counterfactual group. Turning to classrooms, the second paper uses data from the Preschool Curriculum Evaluation Research Study and the Head Start Impact Study (HSIS) to compare the effects that different types of curricula typically used in HS may have on children’s skills. They code curricula into four categories: global (general content), literacy or math (content-specific), and teacher designed. They find that children’s academic skills improved the most in classrooms implementing content-specific curricula compared to the global curricula—the most common curricula type in HS and preschool programs. In the third paper, the authors use data from the HSIS to examine whether the randomized offer to enroll in HS improved the frequency of parent-child literacy activities, and whether this improvement contributed to HS’s impact on children’s vocabulary and decoding skills. Their findings suggest that HS has larger positive impacts on parents’ cognitive stimulation of their children and is an important causal mechanism through which the program improves early language development. The last paper looks at both family and neighborhood contexts to explore how low-income parents’ investments in their children’s learning change over time. The authors use the HSIS sample control group and examine whether parents increase their provision of learning-related materials and activities as their children approach kindergarten. They then test whether the increases in home learning experiences are moderated by neighborhood characteristics. Our participants draw from a range of disciplines including economics, public policy, education, social work, and psychology, and each paper’s authorship is interdisciplinary. We represent multiple academic institutions and policy research organizations across the U.S., in addition to our representation of different genders, ethnicities, and professional experience that includes the foremost scholars in child policy.