Mental toughness has been shown to have relevance in a wide range of performance related fields where distractions, anxiety, and fear are common challenges, however, there remains a dearth of research in the military where the construct has obvious utility. A quasi-experimental trial with treatment (n = 83) and control (n = 90) conditions examined the impact of a psychological skills intervention on observer-rated mental toughness and performance in an elite military context. The results revealed significant differences in the treatment group between pre and post intervention in the use of psychological skills and observer-rated mental toughness. Furthermore, during the selection course, significant differences were evidenced between the treatment and control groups in the use of relaxation and imagery and individual performance.