The "first-grade problem" of the lack of concentration, listening, and following of instruction has been widely identified among Japanese kindergarten students. To promote their executive functioning and self-regulation to prevent this issue, we developed the Social Thinking and Academic Readiness Training (START) program. The experimental group in which the program was implemented contained 79 children (average age = 73.22 months), and the standard practices group contained 70 children (average age = 72.91 months). Before and after the intervention, the children underwent tasks to test their behavioral self-regulation and executive function (working memory). For behavioral self-regulation, a significant interaction occurred between condition (experimental and standard practices) and time (pre- and post-test), suggesting that these 6 START lessons promoted self-regulation. However, no effects were found on either auditory or visual memory. Teacher reports in surveys were consistent with the executive functioning outcomes, reporting improvement in children's concentration, listening, and self-regulation skills.