Social media backlashes have emerged as important phenomena complicating how businesses communicate online and representing significant brand risk. This article demonstrates the value of content analysis and argumentation theory for understanding and responding to social media backlash events, using two examples from the UK fashion industry (hashtags #ThanksItsASOS and #boycottboohoo). The results provide lessons about the way backlashes operate in practice, how to analyze these effectively, and have implications for business approaches to communicating about Corporate Social Responsibility and managing social media. The authors conclude with suggestions for training on social media and CSR for businesses.