A central feature of President Biden’s Build Back Better framework is a proposal to ensure that every child in the United States, if their family chooses to, can attend a public prekindergarten program starting at age 3. Prekindergarten can be offered in various settings—including public schools, private child care centers, or Head Start schools—but in the 2018–19 academic year, about 80 percent of state-funded prekindergarten enrollees attended prekindergarten in a public elementary school building, and more than 50 percent of public elementary schools housed a prekindergarten grade. School-based prekindergarten programs tend to be located in schools that are less economically advantaged and serve higher proportions of students of color than the US average. In public elementary schools in 2019–20, student-level enrollment in prekindergarten is 37 percent of kindergarten enrollment. In light of the shifts in the scope of public education the Build Back Better framework proposes and the resulting changes to the education system’s structure, I take stock of past and present early childhood programming provided in public elementary schools. School-based prekindergarten has implications for both the quality and alignment of early educational experiences, so understanding the landscape will provide policymakers and advocates critical context to inform their decisionmaking. (author abstract)