We investigate the relationship between personal and professional familiarly, team effectiveness, and viability, and how these relationships are mediated by information elaboration in global virtual teams. We further assess whether virtuality moderates the relationships between both types of familiarity and information elaboration. Based on data collected from 63 global virtual supply chain teams, our results suggest that professional familiarity is positively associated with team information elaboration, which in turn relates positively to both manager-rated team effectiveness and team leader–rated viability. Furthermore, team virtuality enhances the influence of personal familiarity on information elaboration, but dampens the relationship between professional familiarity and information elaboration. Our results suggest that professional familiarity is a more salient antecedent of information elaboration in global virtual teams. We discuss the implications of our results for both theory and practice.