This chapter explores the significant role of authenticity in CSA from a strategic communication perspective. It discusses definitions and characteristics of authenticity in CSA conceptualized in recent CSA research and provides real-world examples of CSA initiatives that have been perceived as authentic by audiences. Given the importance of performance evaluation in strategic communication, it introduces guidance on measuring public perceptions of authenticity in CSA for communication researchers and practitioners. Additionally, this chapter proposes theoretical insights and practical recommendations for enhancing authenticity in CSA programs, which can help organizations make a more substantial contribution to positive social change. This chapter also features a case study focusing on how the global outdoor clothing and gear brand, Patagonia, has authentically engaged with social and political issues.