Emerging research in teacher education is showing that cooperating teachers (CTs) have a substantial impact on preservice student teachers’ (PSTs’) future teaching trajectories. In large-scale observational studies of recent graduates in Tennessee and Washington state (Goldhaber, Krieg, & Theobald, 2020; Ronfeldt, Brockman, & Campbell, 2018), researchers found that PSTs who were placed with more instructionally effective CTs were more instructionally effective themselves.