The present study investigates the language phenomenon of stimulus equivalence in children with Autism Spectrum Disorder. Stimulus equivalence is comprised of 3 main concepts: reflexivity, symmetry, and transitivity. Specifically, the researcher evaluated the ability to teach, test, and transfer sequential reflexivity across two participants. Two 4-year-old children diagnosed with Autism Spectrum Disorder participated in the study. Methods were derived from the program: Reflexivity: Pictures – 2A, along with a yes/no response modification to suite both of the participant’s current level of developmental skills. The results suggest that the PEAK-E curriculum was effective in training and testing both children to establish reflexivity across stimulus set one. In addition, both participants demonstrated a transfer of stimulus function to an untrained stimulus set two once the trained stimulus set one was mastered.