Data to quantify the effect that activities such as public service announcements or mass bystander CPR training have on bystander action are limited. Some communities have invested in these types of activities to encourage bystander action with promising results. A marketing campaign may inform potential rescuers about the opportunity to learn life-saving chest compressions. Marketing campaigns may also change the perception of bystanders from a fatalistic view to one that allows the potential for saving the victim, and can also educate about the lack of legal liability. A campaign can also help change the social expectations for action. Messaging should raise an expectation for action.