A multiple probe across participants with an embedded withdrawal single case research design was used to examine the effectiveness of a progressive time delay (PTD) procedure to teach preschoolers with disabilities to imitate their peers during a sculpting play activity. Data indicated the presence of a functional relation between the use of PTD and contingent reinforcement on increased levels of peer imitation across participants; levels also decreased when PTD was withdrawn, although not to baseline levels. Overall levels of peer imitation had a greater magnitude of change than demonstrated in previous research.