With the expansion of school choice systems, policymakers and researchers are increasingly focused on making the school choice process accessible and clear for families. Essentially, school district offices of enrollment and outreach are acting as "choice architects" for parents and students: those who design the environment or organize the context in which people make decisions. This brief offers guidance for current and aspiring school choice architects, including school districts and external support organizations that help families with the school selection process. It draws on insights from MDRC's extensive work with nearly 30 government agencies, nonprofits, and educational institutions around the country testing different choice architectures--the presentation and framing of choices--and distills key lessons for school choice. This practitioner brief is the second publication in a series on school choice, and it is part of the Center for Applied Behavioral Science (CABS) initiative that combines MDRC's expertise in social programs with insights from behavioral science. [For other publications in this series on school choice, see "Lessons for Improving School Choice from Other Policy Areas. Issue Focus" (ED574044) and "Choosing Schools and Choosing Content: The Case of Career and Technical Education. Issue Focus" (ED575649).]