Support for expanding access to high-quality prekindergarten (pre-K) is at an all-time high. Increased investments in early care and education have been spurred in part by rigorous evidence finding that four-year-old students who attend pre-K score higher on assessments of language, literacy, math, and executive functioning skills than children who do not attend pre-K. Yet these initial positive impacts on cognitive and academic skills tend to diminish quickly after pre-K ends and disappear during kinder­garten or first grade.

A growing number of policymakers, practitioners, and researchers have proposed that vertical instructional alignment—or the implementation of standards, curricula, and assess­ments that build on one another as children move from pre-K to elementary school—is a key factor in supporting sustained impacts of pre-K. The Boston Public Schools (BPS) district is the first large school system in the United States to design and implement a curriculum and professional model—called Focus on Early Learning—to align instruction across its public school pre-K program and early elementary school grades. Schools opt in and can choose how much of the curriculum to adopt. Further, BPS’s school assignment process combines information on parents’ preferences for where they would like their child to attend pre-K. When there are more students who prefer a school than there are available spots, this process uses naturally occurring lotteries—which approximate random assignment—to determine which students are assigned to each school. BPS’s implementation of Focus on Early Learning across its pre-K and kindergarten programs, coupled with this school assignment process, present a unique opportunity to rigorously examine the effects of a district-wide rollout of instructional alignment on student outcomes across time.