The UIC Center for Urban Education Leadership (CUEL) brief is an analysis that examines schools that have historically struggled to improve within the context of the Chicago Public Schools SQRP Accountability System. In this research brief, CUEL researchers advance the term 'high churn" to describe a school type that has proven particularly challenging to improve. These schools exhibit comparatively high instability in student enrollment and attendance evidenced in rates of student mobility, chronic absence, and student homelessness. Teacher instability is also common in these schools. Walker and Tozer make the case for envisioning new improvement foci and approaches in these sorts of schools.