The purpose of this research was twofold: to determine whether mental toughness and resilience varied between day hikers, section hikers, and thru-hikers on the Appalachian Trail (AT); and to examine how well these constructs predict successful completion of a 2,186 mile AT thru-hike in one year. Mental toughness and resilience are important constructs to understand given the extreme conditions and possible risks associated with hiking the Appalachian Trail. In order to be a part of the 25% that successfully completes a thru-hike, one must have extraordinary determination to achieve his or her goal, an undeniable sense of self-confidence, and the ability to adapt to difficult demands (Davis, 2012). It was hypothesized that thru-hikers would score higher than day hikers and section hikers on both mental toughness and resilience. Thru-hikers spend the most amount of time on the trail, and generally experience more seasons and hardships; thus, they are also predicted to have higher scores in the subcategories of mental toughness (control, confidence, and constancy). It was also hypothesized that higher mental toughness and resiliency scores would be significant predictors of a successful thru-hike. In total, 405 participants from three categories (day hiker, section hiker, and thru-hiker) completed a demographic questionnaire, the Sport Mental Toughness Questionnaire (Sheard, Golby, & van Wersch, 2009) and the Connor-Davidson Resilience Scale (Connor & Davidson, 2003). One MANOVA and one ANOVA were used to examine differences between mental toughness and resilience, as a function of category of hiker. Additionally, a logistic regression was used to determine if mental toughness and resilience scores could predict whether thru-hikers were successful in completing the trail. MANOVA suggested that day hikers had higher confidence, constancy, and total mental toughness than thru-hikers and section hikers. ANOVA revealed no significant difference between day, section, and thru-hikers on total resilience. Finally, logistic regression suggested that successful completion of the trail cannot be predicted by mental toughness nor resilience scores.