The Vygotskian preschool education program (VPEP) is built around mediation in the context of preschool age-specific activities such as sociodramatic play, constructive play, listening and retelling fairy tales, playing with dollhouses, motor activities, and some others. We used the VPEP as part of the daily curriculum in two pre-K classes at PS 197 in Harlem, New York, to promote the development of children's self-regulation and symbolic thought. Another pre-K class at PS 197 was used as the control group. For pre-and posttests, we administered the Coding and Symbol Search subtests of the Wechsler Preschool and Primary Scale of Intelligence-III (WPPSI-III), which target the ability to self-regulate, and the Block Design subtest of the WPPSI-III, which targets the ability to exercise symbolic thought. The results of the study demonstrate that the VPEP promotes the development of preschoolers' self-regulation and is beneficial for the development of their symbolic thought.