This paper analyzes the reply to the threat of terrorism by Western countries in general. It pays special attention to programs that aim to prevent terrorism from establishing itself in a country and recruiting followers. It points out various errors, dilemmas, and excesses that can make state interventions unsuccessful and even counterproductive. It outlines the types of errors to avoid and programs to adopt in order to be effective. It discusses multiculturalism and social cohesion highlighting their strong and weak points in relation to terrorism prevention. It also offers a critique of the “pyramidal” approach often used to develop strategies against organized crime, drug trafficking and terrorism.