This book investigates what influence online incivility—through user-generated comments on news websites—has on public debate. Built on the premise that public discussions about important topics are vital to a healthy democracy, the book analyzes 3,508 online comments in order to understand what factors in comments make them more susceptible to incivility, defined as nasty remarks rife with profanity. It also examines comments for attributes of deliberation, which are discussions across difference supported by evidence and rational arguments. Using an experiment, the book shows that uncivil comments jumpstart a chain reaction, leading first to negative emotion and then to greater intention to get politically involved. Overall, Online Incivility and Public Debate: Nasty Talk argues that while incivility mars online debate, it may also spark interest in important topics and allow for positive “deliberative moments” of quality discussion.