Abstract
Simultaneous prompting procedures are infrequently published in the behavior analytic literature yet represent a potential method for promoting nearly errorless learning. No research on simultaneous prompting has targeted early skill repertoires for young children with developmental disabilities. The current study compared simultaneous prompting and constant prompt delay procedures on the acquisition of simple listener responses for a 4-year-old male with Down syndrome. Simultaneous prompting produced responding at mastery levels in less than one third of the total sessions required in the prompt delay condition and substantially fewer errors.