This is UChicago Consortium's first comprehensive brief on student teachers and the student teaching experience in Chicago Public Schools (CPS). It synthesizes findings from research done in partnership with researchers from National Louis University, University of Michigan, and Stanford University, using CPS teacher data, along with surveys of student teachers and their mentor teachers, to understand where student teachers were placed, who serves as mentor teachers, and what factors were good indicators of first-year teacher performance. Key findings include: (1) Student teachers' self-reports of their own level of preparation at the end of student teaching were not related to their performance in their first year of teaching; (2) Mentor teachers' instructional support and guidance mattered more than their own qualifications; (3) Student teachers were placed unevenly in schools across the district and were less likely to be placed in low-performing schools and more likely to train in schools that served fewer low-income students; (4) Student teachers were more effective in their first year if their mentor teachers had strong performance ratings, although other mentor characteristics such as National Board Certification status, tenure, and prior mentor experience showed no relationship to student teachers' subsequent performance; and (5) Mentor teachers' assessments of their student teachers' instructional practices were good indicators of student teachers' performance in their first year of teaching. [This policy brief was written with Kavita Kapadia Matsko, Matthew Ronfeldt, Hillary L. Greene Nolan, and Michelle Reininger.]