One of the challenges that global software development teams face is the development of rich and meaningful interactions among members from different countries. Researchers and practitioners in the field are constantly looking for factors that may help organizations understand and mitigate the negative effects that nationality diversity may have on performance in global teams. This paper follows this line of research and proposes prior work ties as a moderator of the relationship between nationality diversity and team performance in global software development teams. In a field study involving 93 global software development teams with members distributed across 5 different countries (e.g., Colombia, Mexico, Brazil, France, and Denmark), nationality diversity was found to have a negative effect on team performance when team members had low prior experience working together. However, nationality diversity did not have a negative effect on performance on teams composed by members with high levels of prior work ties. Moreover, prior work ties exceeded the individual explanatory power of nationality diversity, team dispersion and current experience working together (current project duration) on team performance. This finding suggests that managers should consider how familiar team members are with each other when forming global software development team.