The Principal Investigator (PI) will conduct a program of research for improving the instructional strategies of paraprofessionals working with students with severe disabilities, and will participate in activities to develop expertise in randomized controlled trials with growth modeling, single-case designs, and grant writing. Previous research has identified three key features of professional development that promote fidelity; professional development must include effective training strategies (e.g., modeling, performance feedback, and self-monitoring), be sustained over time, and emphasize generalization of implementation fidelity to authentic contexts. However, there is currently no efficient and effective way to use these features to train large groups of paraprofessionals. The PI intends to develop and test the promise of a multi-tier system of training to improve paraprofessional implementation of systematic instructional strategies (i.e., simultaneous prompting, least-to-most prompting, and data collection and graphing) as well as outcomes for students with severe disabilities, preschool through high school.