<p>There is a growing recognition that flow experiences are shaped by person-situation dynamics, yet little is known about how this motivational state unfolds across the social anxiety spectrum in everyday social contexts. Drawing on theoretical and empirical accounts that link social anxiety to increased self- and threat-focused attention, negative interpretive biases, and strained regulatory capacity, we hypothesized that experiencing social anxiety is negatively related to the emergence of flow in everyday social situations. In addition, we expected this association to be moderated by situational characteristics, such as the familiarity and number of other persons involved. We tested our pre-registered hypotheses by analyzing experience sampling data from 502 participants who completed baseline measures and reported on 5,539 social episodes. In line with our expectations, increased trait and episodic social anxiety were linked to decreased episodic flow. Cross-level interactions further indicated that situational factors moderated this association: Compared to individuals low in trait social anxiety, those with higher levels showed stronger declines in flow in larger and unfamiliar social settings. While our findings offer novel insight into how social anxiety may limit access to rewarding social engagement, we discuss the identified “low-threat” social contexts as potential opportunities to foster flow and build social confidence and competence over time.</p>