Given the critical importance of discrete instructional practices in special education, teacher candidates must be prepared to implement them upon entering the classroom. In preservice teacher education programs, field placements and clinical experiences rarely provide enough opportunities for preservice teachers to gain the proficiency needed to provide effective instruction. In this study, a randomized control research design was used to investigate the effects of a mixed-reality simulation experience compared with traditional classroom practice in the implementation of a system of least prompts. Results suggest that mixed-reality simulation with additional coaching supports significantly improved preservice teachers' implementation of the prompting sequence. Social validity data collected offer insights into the use of mixed-reality simulation in practice with preservice teachers. Limitations and suggestions for future work are discussed.