Motivated by their fear of disapproval, individuals with social anxiety continually monitor their own behaviour during social interactions hoping to prevent dreaded negative outcomes. Ironically, they do evoke less positive reactions from others. This study investigated whether lower engagement in the interpersonal process of joint action by socially anxious individuals leads them to attract less positive ratings by their conversation partners.High socially anxious (HSA; N = 36) and low socially anxious individuals (LSA; N = 36) had separate conversations with a naïve conversation partner (N = 36). Conversations were filmed and analysed for joint action using the conventional manual way and a more exploratory automated way. Conversation partners rated the quality of the interaction and the person they talked to.Conversation partners rated HSA participants less positively than LSA participants. The conventional manual method showed less joint action in conversations with LSA participants and crucially, joint action served as mediator between social anxiety status and general impression, quality of interaction and desire to meet again. These results were not replicated with the automated method.The study used an analogue sample and future research should investigate whether these findings also apply to a clinical sample. Future studies should further explore the utility of automated techniques to measure joint action.Reduced joint action may explain why socially anxious individuals tend to be perceived less positively by others. The findings emphasise the importance of taking an interpersonal and holistic approach to understanding aspects of social anxiety disorder.