Faced with radical political movements, whether influenced by extreme right, far left or radical Islamist ideologies, states and civil society organisations face tough decisions about how best to respond to such movements: essentially, how to hinder their operation without impinging on rights to free speech and association and without generating backfire effects. Furthermore, radical movements also present opportunities for political entrepreneurs to generate political will for their own political agendas. This is the first in a series of two panels in which participants will examine responses to radical political movements from historical and contemporary social scientific perspectives.