The concept of mental toughness has been found to be related to outcome performance measures in sport and other competitive situations. Despite this, little attention has been devoted to understanding the cognitive mechanisms that underlie mental toughness. The current study attempted to identify the cognitive underpinnings of mental toughness using the directed forgetting paradigm, in which participants are given a surprise memory test for material they were previously instructed to forget. Regression analyses showed that mental toughness, as measured by the MTQ48 (Clough, Earle, & Sewell, 2002), did not influence the recall of a to-be-forgotten list, but participants with high mental toughness showed better recall of a to-be-remembered list following instructions to forget the previous list. The superior recall of the to-be-remembered list suggests that mentally tough individuals have an enhanced ability to prevent unwanted information from interfering with current goals. These findings support the proposal that cognitive inhibition is one of the mechanisms underpinning mental toughness.