When hundreds of thousands of Arabs began protesting against their governments, their mobilization did not only surprise their rulers, but even the protestors themselves - as an individual on Facebook put it: “How did this happen?” (al-Thaura al-Arabiyya li-Tahrir Falastin, April 7, 2011) Most analyses of the Arab Spring focus on environmental factors like authoritarianism or economic hardship, or on organizational factors like availability of new technologies or organizational experience of the people. However, these factors change too slowly to explain the unexpected outbreak of the protests. In response, this paper adopts Axelrod’s cognitive mapping approach, and models the Arab Spring as chains of interconnected beliefs. These chains represent the mechanisms by which social influence suddenly mobilized Arabs for revolt as shared beliefs about various factors, including 1. The actions of other people beginning to protest, 2. Present and past events like governmental repression, 3. Values like human dignity, 4. Social grievances like poverty, and 5. Emotions like moral outrage. Cognitive maps are constructed from Arabic Facebook groups, weblogs, and transcripts of Skype interviews. The analysis focuses on protestors from Egypt, where there was governmental change, in comparison with Morocco, where there was no change. It includes three time frames: 1. Beginning of protests, 2. Mass protests, 3. End of mass protests. It shows that protestors in Egypt mobilized around beliefs about 1. The actions of their families and friends in their immediate environment, 2. Governmental violence against the protestors, 3. The suicide of Mohammad Buazizi, and the departure of Ben Ali, 4. Moral outrage about the government, and 5. Values of governmental accountability. Protestors from Morocco shared beliefs about present events of governmental violence, and values of governmental accountability. However, they did not share beliefs about their families and friends protesting in their immediate environment.