Vigilance, or sustained attention, is the ability to maintain attention for extended periods of time. Recently, research on vigilance has focused on identifying individual differences and task design factors that may improve cognitive-based vigilance performance. One such factor is social facilitation, which leads to improved task performance when at least one individual is present. But, relatively little is known about the personality factors, such as extraversion or introversion, which may influence the effects of social presence, and in turn affect vigilance performance. Given this gap in the literature, the present research seeks to determine how personality, specifically extraversion, is related to vigilance performance in the presence of another individual. A total of 39 observers completed a 24-minute vigilance task either alone, in the mere presence of another person, or in the evaluative presence of another person (i.e., an individual monitoring their performance). The results indicated that extraversion was negatively correlated to the proportion of correct detections and sensitivity ( A’).