Recent studies identify gendered differences in communication and collaboration styles which suggest consequences for professional writing classrooms. If, indeed, men tend to stereotype women as clerks, prefer hierarchical collaboration, and value product over process, and, too, if gendered differences tend to increase counterproductive dissent, then the gender balance of writing groups might affect their dominant styles in those respects. However, when I analyzed the behaviors of over sixty student groups in my professional writing classes, I did not find gender balancing to have such effects. Instead, however, I observed other gender-related effects on collaboration: tendencies to stereotype men as technical experts and to self-segregate into gendered working teams. These findings suggest new perspectives on the role of gender for collaborative groups in professional writing classrooms.