Episodic memory (EM) is the content of our personal narratives and is foundational to social communication. Research has repeatedly demonstrated EM challenges in individuals with autism. Meanwhile, it is well documented that a caregiver conversational style known as elaborative reminiscing facilitates EM development in children without autism. This study evaluated the efficacy and social validity of a novel elaborative reminiscing caregiver-mediated intervention to support EM in an 8-year-old girl with autism. Using a mixed-methods approach, we first examined qualitative and quantitative data to evaluate social validity. The caregiver's subjective impressions of the goals, procedures, and outcomes suggested that the parent training had a high degree of social validity. Second, we evaluated child performance on standard assessments of EM. EM performance measures demonstrated improvements in EM following intervention, suggesting that the caregiver's subjective impressions of efficacy were rooted in genuine advancements in her child's EM abilities.