Drawing on data from an ethnographic study of the introduction and implementation of a flexible work policy intended in part to improve gender equality at a STEM professional organization, I develop grounded theory on how managers’ gender shapes their implementation of such initiatives. I identify an <italic>equality policy paradox</italic> in which women managers, who openly support gender equality, are more likely than men managers to limit the policy. This apparent contradiction between intentions and actions is reconciled through an interactional role-based mechanism. Specifically, in this setting women managers encounter barriers to developing technical expertise, client relations, and respected authority. They respond by engaging extensively with subordinates, which allows them to effectively manage by brokering information (as an alternative to technical and client-facing tasks) and cultivating cooperation (as an alternative to formal authority). The policy undermines these interdependent activities; reflecting this, women managers generally oppose it. Men managers tend not to experience these constraints, and they focus on technical and client-related tasks that are largely independent of subordinates. The policy maintains these activities; reflecting this, they implement it. By identifying the equality policy paradox and the mechanism underlying it, this study advances theory on managers’ implementation of equality-related practices and policies as well as theory on gender and management.