Research within the autism spectrum disorder field has emphasized the role of socioeconomic status in shaping parents' ability to access services for their child with autism spectrum disorder. However, research has yet to explore the possible mechanisms underlying this relationship. This study sought to address this research gap by examining the following questions: (1) Does parents' service knowledge mediate the relationship between parent socioeconomic status and parents' autism spectrum disorder service use? (2) What are parents' reported service needs and service barriers, and do these needs vary across higher and lower socioeconomic status groups? Quantitative results from 244 parents of a child with autism spectrum disorder indicate that parents' autism spectrum disorder service knowledge partially mediates the relationship between parent socioeconomic status and parents' autism spectrum disorder service use. Qualitative findings helped to clarify this relationship by suggesting that both high and low socioeconomic status parents are aware of their child's basic autism spectrum disorder needs. However, low socioeconomic status parents more often report needing more information about services and more in-home services and emphasize that a number of structural barriers impede their ability to meet their child's autism spectrum disorder needs. On the other hand, high socioeconomic status parents more often report a need for "higher quality services," possibly reflecting their better recognition of best practice guidelines. These results highlight the need for a multi-pronged approach to tackling unmet service needs within the autism spectrum disorder field.