This article underscores the critical and unquestionable role of parents in the successful treatment of young children with autism spectrum disorder (ASD). The literature emphasizes that parents are the most significant figures in a child’s life, profoundly influencing their development and capacity to acquire new skills. While collaboration between therapists and parents is paramount, the study described in this chapter found that parental characteristics, emotional states, and behavioral patterns can significantly impede a child’s progress. Thus, this chapter advocates for essential interventions with parents to equip them with skills such as executive function, self-regulation, and emotional management, enabling them to serve as effective models for their children. It details how parent-mediated interventions lead to improved child outcomes, enhanced skill generalization, and sustained treatment gains. The chapter also explores factors that compromise treatment effectiveness, such as parental disengagement and a lack of treatment continuity at home. Parents may lack the skills that the child is trying to improve, and thus fail to be good models for their children. The Interactive Play Intervention (IPI) model introduced here offers a structured framework for therapists and parents to identify and work on shared therapeutic goals, fostering deeply internalized change for both child and parent. This resource is indispensable for professionals and families aiming to optimize ASD treatment outcomes through robust parent-therapist collaboration.