Authorship attribution on social media is difficult, especially on Twitter, where the posts have character limitations. The increased prevalence of disinformation on social media motivates us to study how much of an 'authorship footprint' is left on social media by celebrities vs. non-celebrities and various professional groups. In this talk, Dr. Siobahn Day Grady will discuss authorship within online social networks and present examples of different groups, their footprints on these networks, and machine learning algorithms performance in determining professional groups' authorship.