Districts around the country are increasingly experimenting with the design and launch of autonomous district schools as a way to increase innovative, high-quality school options; bring decision-making closer to students; retain talented leaders; and prevent students and families from leaving the district for charter schools. In this report, the authors share a case study of one district using autonomous district schools as a part of its district improvement strategy: San Antonio Independent School District (SAISD) in south central Texas. This document aims to inform education leaders -- especially district administrators, school principals, and philanthropists -- about a promising (but still largely unproven) education improvement strategy, the key steps in implementing this strategy, and what the authors have learned in supporting the early implementation of this work. The authors offer five key lessons from their work with SAISD for districts considering autonomous schools as a strategy: (1) Build maximum autonomy into the application around the instructional program; (2) Ensure leaders receive robust support to shift mindsets and skills into this new role; (3) Empower a central office team to efficiently clear obstacles; (4) Invest in extensive stakeholder engagement; and (5) Build leaders' capacity to manage a governing board (this is far outside leaders' experience, and they will need a lot of support to do this well). The authors believe that only if districts considering an autonomous schools initiative take note of the five lessons learned from this work with SAISD and make these investments thoughtfully and well, this promising strategy will reach its potential to improve education for the most underserved students.