The development of sustained attention in the preschool years is not yet fully understood. Delineating age-related changes of attentional proficiencies and deficiencies is important for understanding atypical developmental trajectories, specifically in neurodevelopmental disorders that are characterized by attentional difficulties. The objective of the current study was to develop preschool-appropriate measures for assessing sustained attention and to chart developmental changes in attention in early childhood. Method: Using adapted computerized paradigms, the present study investigated age-related changes in visual and auditory sustained attention in seventy typically developing children aged 3 to 6 years. Results: The results indicated that similar age-related gains in performance emerged across both visual and auditory attention tasks. Conclusion: The findings suggest that the adapted measures developed in this study are sensitive enough to capture developmental variations in attention performance.