Revolutionaries have challenged nearly every Middle Eastern regime since 2010. What are the factors that galvanize demonstrators? What explains why some countries escape unrest (e.g., Saudi Arabia and Morocco), why some regimes succumb to protestors (e.g., Tunisia and Egypt) while others either repress them (e.g., Iran) or find themselves embroiled in civil wars (e.g., Libya and Syria)? Which Middle Eastern countries are currently most ripe for revolution? In particular, what are the chances for regime overthrow in Iran?