The involvement of paraprofessionals in the education of students with intellectual and developmental disabilities (IDD) has been both complex and controversial. Many scholars and advocates have raised concerns about the roles these staff members play in schools and the degree to which there is empirical support for their direct work with students. We conducted a systematic review of the literature to address two primary questions: To what extent have paraprofessional-implemented educational practices been shown to improve outcomes for elementary and secondary students with IDD, and what professional development strategies enable paraprofessionals to implement these strategies with fidelity? These studies indicate paraprofessionals, when given adequate training, are capable of effectively implementing a number of educational practices that result in improved academic and social outcomes, specifically, teaching communication skills, reducing problem behaviors, and increasing independence for students with IDD. Follow-up training and support, modeling, and performance feedback were prominent training components across most studies in this review and are validated in the broader research literature. However, limitations leave many questions unanswered about how to best train and support paraprofessionals. We discuss recommendations for preparing paraprofessionals who work with students with IDD, as well as future directions for research.