Whereas a growing interest in the development of attentional flexibility (AF) and in perseverative behavior, being one marker of this component, exists in neuropsychological studies and in the domain of developmental psychopathology (e.g., PKU, infantile schizophrenia, autism and Parkinson's disease) (Pennington & Ozonoff, 1996; Stahl & Pry, 2002), only a few studies have concerned themselves with this subject in normal children. It is thus of interest to add more empirical data to the existing literature in this domain. Therefore, the aim of our study was to explore the development of AF and of perseverative errors in young preschool children with normal development, aged 1.5 to 6 years. Using set-shifting tasks of increasing difficulty level, three age groups were compared with respect to their AF skills.Results show a developmental factor underlying AF, with different levels of this form becoming more and more complex with age, ranging from a rudimentary visual form to a complex representational form of flexibility. Overall, few perseverative errors occurred and they decreased with age. Results are discussed from a developmental and neuropsychological perspective.