Patagonia’s 2014 documentary DamNation marks a compelling and unconventional milestone in the evolution of corporate social responsibility (CSR) as public relations practice. The company drew from commercial acumen but also grassroots organizing, moving its CSR initiative closer to a form of social and environmental activism. This study, especially relevant for strategic communicators focused on CSR and sustainability issues, assesses DamNation’s impact upon Patagonia’s audience in terms of message effectiveness, company reputation, and willingness to act on Patagonia’s behalf in addressing the issue of dams. An online survey with experimental conditions was used to measure audience views on Patagonia’s campaign, as well as differences between those exposed to such company-sponsored activism and those who are not. Findings from the study shed light on both emerging CSR practices and integration of grassroots activism approaches.