In recent years, there has been an unprecedented boom in online hate speech and extremism. Grave though it is, this global issue has not gone unchallenged. Rather, it has given rise to an international archipelago of organisations, civil society groups, and individuals that proactively engage in counter-speech – i.e., “a common, crowd-sourced response [that] argues, disagrees, or presents an opposing view to extremism or hateful content” – and other more direct measures, which can broadly be termed counter extremism (CE). Adopting a comparative case study approach, this report evaluates counter-speech and CE in three European countries – the United Kingdom, Germany, and France.