Developmental research suggests that children's cognitive inhibition increases in efficiency with age, which leads to better performance in memory, problem solving, reasoning, decision or emotional control. Over several decades, directed forgetting has been proven to be among the reliable methods used for studying intentional inhibitory processes in cognition. This study has the general aim to investigate the development of cognitive inhibition during secondary school. In order to accomplish this, I used directed forgetting tasks in two procedural versions: list and item-by-item. In Experiment 1, fifth and eighth grade students participated in an item-by-item directed forgetting task. The directed forgetting effects observed in this procedure are usually interpreted in terms of encoding differences or differential rehearsal of the studied items. In Experiment 2, fifth and eighth grade students participated in a list directed forgetting task. The directed forgetting effects observed in this case are interpreted in terms of retrieval inhibition. The overall results suggest that the ability to intentionally control the mnesic access of irrelevant or unwanted information increases with age during secondary school.