Advocacy is intended to change people's attitudes and behavior. Yet the psychological and behavioral consequences of advocacy have rarely been considered. Across 3 experiments (combined N = 934) in the contexts of debates around racial discrimination and abortion, we investigated if and how exposure to advocacy can influence collective giving responses: self-reported willingness to make donations congruent with one's beliefs on the issue and actual giving behavior. Reading tweets from one's own side of a contentious debate sometimes indirectly mobilized collective giving responses by enhancing perceptions of efficacy and ensuring people empathized and identified with highlighted victim groups. Simultaneously, however, supporting advocacy sometimes inadvertently suppressed action by reducing anger and perceived injustice. Results therefore show that advocacy can simultaneously mobilize and demobilize support. However, effects were not found consistently across contexts and donation measures. Overall, mobilization pathways were stronger, especially on donation behavior and in the context of the abortion debate. Results suggest advocacy can work broadly as intended: by influencing the attitudes and behaviors of audience members. Online