Gender differences in task allocations may help sustain vertical gender segregation in labor markets. If women hold more non-promotable tasks then they may progress more slowly than men in organizations. Examining environments where a volunteer must be found for a task that everyone prefers be completed by someone else (writing a report, serving on a committee, etc.) we find that, relative to men, women more frequently volunteer, more frequently are asked to volunteer, and more frequently accept requests to volunteer. These differences are consistent with the belief that women, less than men, say ‘No’ to request to perform non-promotable tasks.