Although paraprofessionals have become an increasingly integral part of special education services, most paraprofessionals lack training in evidence-based instructional strategies. We used a randomized contolled experimental design to examine the efficacy of a professional development training package and its individual components to equip 25 paraprofessionals to implement constant time delay. The effect of the training package on implementation fidelity was statistically significant and large in magnitude (d = 2.67; p < 0.001). Video modeling and coaching components were effective, although the effect of coaching alone (d = 2.23; p < 0.01) was larger than video modeling alone (d = 0.55; p = 0.18). Recommendations for further refining effective professional development opportunities for special education paraprofessionals are offered along with discussion of future research needs.