Zachary C. Steinert-Threlkeld is a PhD Candidate in political science at the University of California – San Diego. He studies political violence, with a particular focus on mass protest. His research takes advantage of social media data to understand individual-level behavior at a daily level, and he uses these data to understand dynamics of mobilization, elite behavior, and state repression. His dissertation focuses on the Arab Spring and Ukraine’s Euromaidan protests. In it, he develops a theory of protest tactics that explains how activists substitute between online media and offline activity; uses millions of tweets to show that protest mobilization can occur spontaneously, without organized leadership; and shows that, contrary to prevailing wisdom, social media enable state repression as much as they hinder it.