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 well-known, high-quality 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. As part of the Expanding Children's Early Learning Network (ExCEL) project, MDRC is partnering with with the Boston Public Schools (BPS) Department of Early Childhood, the University of Michigan, and the Harvard Graduate School of Education to understand how BPS's reforms to align instruction across the early grades supported teaching and learning. The purpose of this brief is to assess the feasibility of using naturally occurring lotteries to evaluate the effects of BPS's "Focus on Early Learning" approach on students over time; results from a full impact study estimating effects on student outcomes will be released in 2023. The brief begins by presenting background information on the approach, the motivation for the study, and the project's core research aims. It then explores three issues related to the study's feasibility that are critical for determining whether lotteries can be used to answer policy-relevant questions in a rigorous way. The brief concludes by discussing whether this study is successfully set up to draw causal conclusions about the impacts of a district-wide rollout of instructional alignment across the early grades while also producing results that are generalizable--and relevant--to the broader population of BPS pre-K students and schools.