This study will focus on examining the supports required to enable community Senior JASPER Trainers to support the training and development of junior interventionists throughout the province of Newfoundland and Labrador, Canada. The study will examine the training and supports delivered by Senior Trainers to help junior interventionists provide a targeted social communication intervention (JASPER: Joint Attention, Symbolic Play, Engagement, and Regulation) with children with autism spectrum disorder (ASD). Children's engagement, play, and social communication outcomes will be examined as well as the influence of junior interventionists' intervention implementation on children's outcomes. Further, the study will examine the supports required to help junior interventionists who demonstrate slower gains in implementation fidelity after the first three months of standard support. Interventionists who are slow to gain implementation fidelity will be randomized to either (a) enhanced feedback plus peer support or (b) enhanced feedback plus intensive refresher course.