Book excerpt: Revolutions upset the existing international order. But not all revolutions upset it equally. In Revolutions and Revolutionary Waves, Mark N. Katz focuses on what is arguably the most disruptive kind of revolutionary wave: the kind that spreads by sparking "affiliate revolutions" in other countries. Katz compares three revolutionary waves--Marxist-Leninist, Arab nationalist, and Islamic fundamentalist--to unearth the complex relationships of revolutionary actors within them. He also makes predictions on the fate of the Islamic fundamentalist wave, arguing that it suffers from the same internal problems and contradictions that led to the collapse of the Marxist-Leninist and Arab nationalist revolutions. Revolutions and Revolutionary Waves is an outstanding contribution to the study of revolution, Middle East politics, and international relations.