Donatella della Porta is Professor of Sociology at the European University Institute, Italy.

This volume compares four types of clandestine political violence: left-wing, right-wing, ethnonationalist and religious fundamentalist.

1. Political violence and social movements: an introduction; 2. Escalating policing; 3. Competitive escalation during protest cycles; 4. The activation of militant networks; 5. Organizational compartmentalization; 6. Action militarization; 7. Ideological encapsulation; 8. Militant enclosure; 9. Leaving clandestinity? Reversing mechanisms of engagement; 10. Clandestine political violence: some conclusions.