© Hammill Institute on Disabilities 2020.We examined the effects of the least-to-most prompting (LTM) procedure with contingent imitation (CI) on increasing the frequency and diversity of pretend play in children with autism spectrum disorder (ASD) using a multiple probe across toy sets single-case research design. Three children with ASD aged 5 to 6 years took part in the study. LTM was functionally related to increases in the frequency and diversity of children’s pretend play. Novel pretend play behaviors, sequences, and vocalizations also increased for all children. Importantly, all children maintained the target skills 1, 2, and 4 weeks after the intervention and generalized them across their homes, mothers, and different toys.