Many novice teachers learn to teach “on the job,” leading to burnout and attrition among teachers and negative outcomes for students in the long term. Preservice teacher education is tasked with optimizing teacher readiness, but there is a lack of causal evidence regarding effective ways to prepare new teachers. In this paper, we use a mixed-reality simulation platform to evaluate the causal effects and robustness of an individualized, brief, and highly directive coaching model for candidates enrolled in a university-based teacher education program as well as for undergraduates considering teaching as a profession. Across five conceptual replication studies, we find that short, targeted, and directive coaching significantly improves candidates’ instructional performance during simulated classroom sessions and that coaching effects are robust across different teaching tasks, study timing, and modes of delivery. However, coaching effects are smaller for a subpopulation of participants not formally enrolled in a teacher preparation program. These participants differed in terms of prior experiences learning about instructional methods, suggesting that coaching in isolation is not as effective without corresponding coursework on targeted practices. Taken together, our five studies provide encouraging evidence that teacher preparation can be an important time for rapid skill development when candidates are given targeted practice opportunities and corresponding support. Although we often think that practice has to happen in real classrooms with real students, we provide robust evidence that “the work of teaching” can be incorporated into teacher education coursework. We highlight implications for research and practice.