Women who participate in mixed-gender, antifeminist movements are not a homogeneous group of actors who face no identity-based conflicts when they mobilize for these causes. Using 23 in-depth interviews with women involved in the American fathers’ rights movement—which has as its goal the reformation of child support and child custody laws in ways that are more favorable to men and less favorable to women—I argue that mixed-gender, antifeminist activism has the potential to produce high levels of tension for female participants between their various social identities and their collective movement identity. Indeed, almost half of these women elaborate on how two particular manifestations of their social identities—as simultaneous members of other feminist groups and simply as women—clash with the collective identity generated by the fathers’ rights movement. Ultimately, these women coped with these competing allegiances in a variety of proactive ways. In contrast, the other half of the sample experienced no such tensions. These differential patterns of identity-based conflicts are suggestive of the hazards associated with a social movement's efforts to attract a wider membership base over time.