Executive functions (EF) provide top-down control of thoughts, emotions, and behaviors. Such abilities are related to learning, emotional control, and adjustment. A promising line of research on EF examines early interventions to promote EF development; however, in developing countries, evidence of EF-related early interventions remains limited. In this study, 70 five-year-old preschool children and their four teachers were divided into an experimental group (EG) and a control group (CG). EG teachers were trained to administer the Intervention Program for Self-regulation and Executive Functions in a classroom context over four and a half months. All children were assessed with tests to measure EF at two time points: before and after the intervention period. EG children exhibited significant gains in attention and inhibition post-intervention. The results suggest that the intervention program is more effective at promoting EF development than the regular curriculum. This finding may have practical relevance to public politics in education, primarily in disadvantaged contexts, as in certain developing countries.