This chapter highlights how Facebook can enable researchers to understand their audiences, why people choose to share content with friends and family and what that means for the kind of health content that works on Facebook. As the primary case study, the chapter describes an online graphic novel about depression called the Black Dog. The chapter highlights research that revealed three key insights on why people share entertainment-education campaigns like the Black Dog on social media. There are three primary reasons that people share content on Facebook: (1) to define who they are, (2) to be of value to their friends, and (3) to make a positive difference in their community or the world.