Tunisia has many advantages over other Arab states: no deep ethnic or sectarian divisions; no oil wealth that distorts the economy and draws foreign interference; a tradition of moderate Islam; widespread literacy; a small, apolitical army. ... Democracy didn’t turn Tunisian youths into jihadis, but it gave them the freedom to act on their unhappiness. By raising and then frustrating expectations, the revolution created conditions for radicalization to thrive. New liberties clashed with the old habits of a police state—young Tunisians were suddenly permitted to join civic and political groups, but the cops harassed them for expressing dissent. Educated Tunisians are twice as likely to be unemployed as uneducated ones, because the economy creates so few professional jobs. ... Salafis follow literalist interpretations of the Koran and maintain that all spheres of society must be ruled according to strict Sharia law (which, for example, promotes the removal of women from the public sphere). Those who support jihad make selective theological and legal arguments to justify violence against the perceived enemies of Islam. The targets do not change: the West, Jews, Shiites, the secular governments and security forces of Islamic countries, and Sunni Muslims who are deemed apostates. But the factors that drive young men and women to adopt Salafi jihadism are diverse and hard to parse: militants reach an overwhelmingly reductive idea by complex and twisted paths. ... Part of the success of ISIS consists in its ability to attract a wide array of people and make them all look, sound, and think alike. ... In Tunisia, leaving to wage jihad has become a social phenomenon. Recruitment spreads like a contagion through informal networks of friends and family members, and the country is small enough so that everyone knows of someone who has disappeared.