People differ in many different ways – different nationalities, different genders, different ages. But do these differences matter when it comes to leadership, teamwork, patterns of interaction, cognitions? In this research project, we look at whether women and ethnic minorities are marginalized in organizational settings (Mehra, Kilduff, & Brass, 1998). We examine whether teams with leaders from different countries think differently and perform better or worse than teams more homogenously structured (Kilduff, Angelmar, & Mehra, 2000). We examine whether demographic diversity produces fragmentation in teams, and what the consequences of this fragmentation might mean for performance (Balkundi et al.2007).