In the digital age, a new breed of strategic communications campaign has emerged which blurs boundaries between factual media, entertainment, marketing and advocacy. Strategic impact documentaries (SIDs) are social issue campaigns with a documentary text at their core. They invite the audience to join a cause as much as view a text, using both online and offline strategies to achieve their goals. The way audiences engage with media messages in this new ecosystem, and the implications for public deliberation of social issues, is not fully understood, however. In a mixed methods case study analysis, the Facebook audience engagement strategies used by SID were examined. The results highlight the temporal nature of social media audience engagement and the audience’s changing relationship with both the media text and its producers and provide insight into the way social issues are discussed and deliberated on by audiences in the online sphere.