In young adults at university, social interaction anxiety has been linked to elevated risk of alcohol-related problems, as has alexithymia. The present study sought to assess whether social interaction anxiety is, like alexithymia, associated with the primary motive of drinking to cope with negative affect. There were 126 undergraduates (76 females, 50 males), aged 18–25 years, who were recruited from two southeast Queensland universities to complete validated self-report measures of problematic drinking, alexithymia, drinking motives, and social interaction anxiety. As predicted, social interaction anxiety was positively related to problematic drinking and coping motives for drinking. Alexithymia mediated the relationship of social interaction anxiety with coping motives. Findings were consistent with a developmental hypothesis of the links between social anxiety, alexithymia, and drinking motives. Given the cross-sectional design of the current study, longitudinal research is ultimately needed to confirm such interpretations of alexithymia and alcohol use among socially anxious young adults at university.