Prison reformers have long been aware that the cellblock is a school for criminals, the shadow campus where the petty offender graduates into organized crime. Yet strangely, the same insight has for the most part eluded jail keepers in countries now targeted by Islamic terrorists. The usefulness of prisons as universities for terrorists, however, has not escaped Islamic radicals. They have become increasingly sophisticated in their operational methods, especially in devising ways of recruiting and training those who spearhead their assaults. Last spring’s devastating train bombings in Madrid, the mishandling of which led to the electoral defeat of the sitting Spanish government, illustrate the phenomenon. A principal conspirator, Jose Emilio Suarez Trashorras, a Spanish mineworker, was not religious or politically aware when he was jailed in 2001 for a drug offense. Incarcerated in the same prison was Jamal Ahmidan, a young Moroccan living in Spain, also convicted of a petty crime. Once in prison, however, both the nominally Christian Trashorras and the nonobservant Muslim Ahmidan enthusiastically embraced radical Islamic fundamentalist beliefs and were recruited into an al-Qaeda–linked Moroccan terrorist group, Takfir wa al-Hijra. The imprisoned Ahmidan quickly gained a leadership position in the cellblock, and on emerging from prison both men were absorbed into an extensive and well-organized radical Islamic organization that trafficked heavily in drugs to support its terrorist activities. Later, Ahmidan led the cell that carried out the Madrid bombings, while Trashorras supplied the explosives and helped plant the 13 backpack bombs that killed 191 people and injured hundreds of others on four Madrid trains crowded with early-morning commuters. The use of prisons as a means of recruiting new members into terrorist organizations while providing advanced training to existing members is hardly a new phenomenon. For more than 30 years, European countries have been beset by a variety of nationalist and leftist terrorist groups, some of them highly sophisticated organizations with large rosters of combat and support personnel. Two groups in particular stand out: the Provisional Irish Republican Army, or Provos, which has waged a sustained campaign to achieve a united Ireland, and the Basque Euskad Ta Askatasuna (ETA), which first fought against the Franco government and now battles Spain’s democratic government in its quest for Basque autonomy. Both are classic paramilitary terrorist organizations, with integrated command structures and a high degree of group cohesion, characteristics that persist in a prison setting. Leftist revolutionary groups were organized differently. The Red Army Faction in West Germany, Action Directe in France, and the Red Brigades in Italy, which were active from the late 1960s until the early 1980s, eschewed the paramilitary model and relied instead on a looser cellular structure, with collective decisions guided by charismatic leaders. Targeted governments countered with extensive antiterror legislation and intern-