Approximately 1 in 68 children is diagnosed with Autism Spectrum Disorder (ASD; Centre for Disease Control, 2012). One of the diagnostic criteria for ASD is stereotyped or rigid, repetitive patterns of behaviour (APA, 2013). It has been well documented that if left untreated, stereotypy can persist throughout the lifespan (Matson & Rivet, 2008) and have detrimental impacts on health (Ball, Campbell & Barkemeyer, 1980), learning (Morrison & Rosales-Ruiz, 1997), and social functioning (Jones, Wint & Ellis, 1990). There is growing evidence that an intervention package including reinforcement and blocking is effective in reducing stereotypy in children with ASD (e.g., Mueller & Kafka, 2006). Ongoing research with particular focus on the effectiveness of this intervention in the natural environment with caregivers is justified. Caregivers have the greatest potential to act as enduring behaviour change agents in a child's life. However, there is a lack of research demonstrating the effectiveness of caregivers implementing evidence-based interventions (Drew et al., 2006). The proposed research will use a large-scale randomized control trial to investigate the effectiveness of a caregiver implemented intervention package to target stereotypy in young children with ASD. It is hypothesized that training caregivers to utilize reinforcement with blocking will result in a reduction of stereotypy. In addition, the success of the intervention may lead to a reduction in caregiver stress. Identifying effective interventions that can be successfully implemented by caregivers will likely lead to improved health outcomes for children with ASD and their caregivers as well as overall reduced treatment costs.