Cognitive models of social anxiety posit inaccurate appraisal of emotional states as a core feature. Such inaccurate appraisal also characterizes alexithymia, a trait defined by difficulties in identifying and describing emotional feelings and an externally oriented thinking style. Because both social anxiety and alexithymia have been linked to alcohol misuse and deficient theory of mind, the degree to which alexithymia might account for these associations with social anxiety merits investigation. The current study explored relationships between social anxiety (specifically social interaction anxiety), alexithymia, problematic drinking, and theory of mind after controlling for comorbid depression in a nonclinical sample of 242 participants (93 men) ranging in age from 18 to 35 years (M = 23.22 years, SD = 4.48). They completed an online questionnaire battery that included well-known measures of social anxiety (Social Interaction Anxiety Scale), alexithymia (Toronto Alexithymia Scale 20), theory of mind (Reading the Mind in the Eyes Test Revised), depression (Depression Anxiety Stress Scales-Depression Scale), and problematic drinking (Alcohol Use Disorders Identification Test). In hierarchical regression models, social anxiety predicted alexithymia even after depression and demographic factors were controlled for; alexithymia mediated relationships between social anxiety and both problematic drinking and deficient theory of mind. Assessment of alexithymia in those with social anxiety may potentially offer insight and directions for treatment.