Social anxiety (SA) is characterized by anxious symptomology and fear during social situations, but recent work suggests that SA may not necessarily be associated with negative interpersonal and intrapersonal outcomes in support contexts. The current research investigates the discrepancies between self-perceptions, behavior, and physiological responses associated with SA in social support conversations with close friends. Specifically, we examined the associations between SA and positive and negative affect, perceptions of demands and resources, and responsiveness. Additionally, we used the biopsychosocial model of challenge and threat to understand the physiological responses associated with SA. Participants (79.9% White, 9.8% Black or African American, 10.3% Multiple races or other; 78.7% Female), totaling 172 undergraduate friend dyads, completed self-report measures and had physiological responses recorded while they discussed a problem unrelated to the friendship. Trained coders rated responsive behaviors exhibited during the conversation. Results revealed that greater SA was associated with greater negative perceptions of social interactions (greater negative affect, fewer perceived resources, and greater perceived demands). However, cardiovascular reactivity and behavioral responses within the conversation, as well as perceptions of partners' behavior after the conversation, contrasted with these negative perceptions. Indeed, greater SA was associated with greater sympathetic arousal (indicative of greater task engagement), but not with greater challenge or threat, and SA was not associated with perceived partner responsiveness or responsive behaviors. These results add to the growing body of research that suggests people with greater SA show inconsistencies between their conscious appraisals of social situations and their physiological responses.