Executive functions (EF) refers to the skills needed to plan, initiate, implement, and monitor intentional behaviors. They include inhibition, working memory, cognitive flexibility, selective attention, planning, and organization. The focus of this study was the selective attention, refered to the ability to select relevant stimuli, inhibiting distractors. The study investigated the relationship between performance on a task of selective attention and the development of children aged 4 to 6 years. The participants were 85 children of a public preschool, assessed by the Cancellation Attention Test (CAT). Results revealed that the performance of children increased with the progression of age and school grade. The performances in various parts of TAC showed several significant correlations with each other, showing the consistency of the instrument. The study complements the literature on the development of selective attention, even at very early age.