The current study examined the tripartite model of anxiety and depression in relation to social phobia in a nonclinical sample of adolescents (ages 13-17). Adolescent/parent dyads participated in a semistructured interview and completed self-report measures of the tripartite constructs and social anxiety. Adolescents gave an impromptu speech, and heart rate was monitored. Low positive affect, high negative affect, and high physiological hyperarousal were characteristic of adolescents diagnosed with social phobia; adolescents with elevated social anxiety symptoms who did not meet criteria for social phobia did not evidence low positive affect. Heart rate reactivity during the speech was not significantly correlated with social anxiety symptomatology or with self-reported physiological hyperarousal. (Contains 5 tables.)