The recent Every Student Succeeds Act (ESSA) requires states to identify and turn around their lowest performing schools, but it breaks somewhat from prior policies by granting states significant autonomy over how they identify and turn around these schools. This mixed-methods study, which draws on administrative, qualitative, and survey data, examines the effectiveness of Michigan's approach to school turnaround under ESSA. We find that students in turnaround schools experienced significant achievement gains in math and to a lesser extent in English language arts (ELA), with effects concentrated among the lowest achieving students. Analyses of qualitative and survey data suggest that these outcomes were influenced by state-level supports, strategic planning, the threat of accountability for continued low performance, and improved leadership quality in turnaround schools.