Not all types of SB are equal when examining optimal cognitive development in preschoolers. Frequent breaks from sedentary time were associated with better cognitive development. Encouraging more frequent breaks to interrupt prolonged SB may be a viable strategy for reducing sedentary time to promote optimal cognitive development. These findings should be further validated in larger prospective studies. • Sedentary behavior is not advantageous for cognitive development. • Not all types of sedentary behavior are harmful. • Active sedentary behaviors are beneficial to overall cognitive development, but screen-based active sedentary behaviors may negatively impact some areas of cognitive performance. • Cognitive abilities in preschoolers are associated with sedentary breaks, but not with sedentary bouts.