As the number of unmarried adults in the workforce is on the rise, employees increasingly have to navigate lifestyle differences between single, married, and divorced members of their work groups. To understand the impact of this new form of diversity in groups at work, we introduce the concept of marital diversity as an important predictor of group performance outcomes. We argue that marital diversity may benefit group outcomes by providing members with complementary life experiences and skills, without instigating the stereotyping or conflict often associated with other less mutable forms of diversity. In Study 1, an archival study of rock bands reveals that marital diversity positively affects group outcomes when band tenure is high. In Study 2, this pattern is replicated in a study of project groups. Overall, the studies show that marital diversity can positively affect groups, especially groups with longer tenure.