The present study examined the validity of a newly developed instrument, the Mental Toughness Scale for Adolescents, which examines the attributes of challenge, commitment, confidence (abilities and interpersonal), and control (life and emotion). The six-factor model was supported using exploratory factor analysis (n = 373) and confirmatory factor analysis (n = 372). In addition, the mental toughness attributes correlated with adolescents’ academic motivation and engagement (n = 439), well-being (depression and anxiety; n = 279), and test anxiety (n = 279), indicating relations with a number of affective, cognitive, and behavioral dispositions, and demonstrating relevance in education and potentially mental health contexts.