It is known that executive functions are impaired in children with ADHD symptoms, especially key components such as working memory. Moreover, is unclear whether working memory stimulation has the same positive effect in children without ADHD symptoms, children with slight symptoms, and those with strong symptoms. We compare the effects of stimulation program for children who have no symptoms of ADHD, children with slight symptoms of ADHD and children with strong symptoms of ADHD. The study utilized a pre-postest design, in which a sample of randomly children selected at the classroom level. The investigation considered two times points, one at the beginning of the pre-kindergarten school year and another 6 months later, by the end of the school year, using 3 intervention groups. The groups display initial differences (p<.001). After the intervention, no differences are observed between the mean working memory scores of each group, controlling for the initial differences using a covariance analysis (ANCOVA). The results are discussed recognizing working memory stimulation has a positive effect on working memory development (Rojas-Barahona et al., 2015), and the impact is different in children who has ADHD who display stronger symptoms than in asymptomatic ones or in those with slight symptoms