The current study aimed to understand parents’ perceptions of the effects of early intensive behavioral intervention (EIBI) based on the principles of applied behavioral analysis (ABA) and the lasting outcomes for their children with Autism spectrum disorder (ASD). In particular, this study sought to examine parent perceptions of the relationship between the intensity of ABA interventions and current autism symptom severity, adaptive functioning, and school placement. The current study employed a convergent parallel mixed-methods design, which consisted of collecting, analyzing, interpreting, and combining both quantitative and qualitative data. Overall, results suggested that the intensity of previous ABA interventions was a unique predictor of current school placement. Additionally, results suggested that the intensity of previous ABA interventions was a unique predictor of adaptive skills, which was supported by parent interviews. However, the intensity of previous ABA interventions was not a unique predictor of current autism severity. Parent responses to interview questions revealed the imperative nature of the interventions and their effect on service delivery for their children with ASD. Overall, this study provided an increased understanding of parents’ perceptions of the effectiveness of EIBI, which in turn may be central to understanding service utilization.