Scholars often use survey data to study how discussion networks influence electoral turnout, typically demonstrating that individuals with more participatory networks are themselves more likely to vote. This conclusion rests on the assumption that errors in individuals’ self-reported turnout are unrelated to the composition of their discussion networks. We call this assumption into question, arguing that an individual’s perception of the social desirability of turnout depends on the engagement levels of their associates. Thus, both turnout and turnout over-reporting should increase with network participation levels. We provide experimental and observational evidence that the well-known problem of turnout over-reporting in surveys is driven by characteristics of individuals’ discussion networks. We go on to show that analyses failing to account for this pattern may obtain biased estimates of the relationship between individuals’ discussion networks and their self-reported turnout. This study therefore helps explain how social networks influence social desirability and provides empirical insight into the consequences of this relationship for the study of social influence in political behavior.